Head-to-head comparison

Claude Sonnet 5 vs. DeepSeek-V4.1-Flash

Compare published benchmark results from matching versions and cohorts, API pricing, and technical specifications. Any documented test setup differences remain visible.

shared result series: 207
distinct benchmarks: 26
latest retrieval: 2026-10-15

First modelSecond model

Specifications

General specifications

Release date, availability, context window, architecture, and published parameter counts at a glance. Undisclosed details remain marked as unavailable.

Specifications for Claude Sonnet 5 and DeepSeek-V4.1-Flash
Attribute	Claude Sonnet 5	DeepSeek-V4.1-Flash
Provider	Anthropic	DeepSeek
Released	Jun 30, 2026	Sep 10, 2026
Availability	Active	Active
Model type	Proprietary	Open Weights
Parameters	Not published	552B
Architecture	Not published	Mixture of Experts
Context window	1,000,000 tokens	1,000,000 tokens
Knowledge cutoff	January 2026	Not published
Technical sources	Model, Context	Model

Pricing

API pricing compared

The table compares official standard API rates per 1M tokens, including published cache pricing. Batch, fast, priority, regional surcharges, tool calls, and cloud platform pricing are excluded.

API pricing for Claude Sonnet 5 and DeepSeek-V4.1-Flash
Price type	Claude Sonnet 5	DeepSeek-V4.1-Flash
API input	$2	$0.15 (Off-Peak)
API output	$10	$0.6 (Off-Peak)
Cache read	$0.2	$0.003 (Off-Peak)
Cache write (5 min.)	$2.5	Not listed
Cache write (1 hr.)	$4	Not listed
Price verified	09/22/2026 Source	09/23/2026 Source
DeepSeek-V4.1-Flash: peak pricing is $0.3 input / $1.2 output per 1M tokens during Mon, Tue, Wed, Thu, Fri, 01:00-04:00 UTC; Mon, Tue, Wed, Thu, Fri, 06:00-10:00 UTC; off-peak rates apply at all other times.

Claude Sonnet 5DeepSeek-V4.1-Flash

API inputUSD per 1M tokens, base tier

Claude Sonnet 5$2

DeepSeek-V4.1-Flash$0.15

API outputUSD per 1M tokens, base tier

Claude Sonnet 5$10

DeepSeek-V4.1-Flash$0.6

Cache readUSD per 1M tokens, base tier

Claude Sonnet 5$0.2

DeepSeek-V4.1-Flash$0.003

Key to the marks:better valuebetter, but not conclusivetie

Pricing by provider

Direct developer pricing and provider endpoint tariffs routed through OpenRouter are listed separately. Prices are in USD per 1M tokens. Context-dependent direct tiers plus regional, Flex, Priority, and other OpenRouter tariffs remain individually identifiable.

Provider pricing for Claude Sonnet 5 and DeepSeek-V4.1-Flash
Model	Provider	Purchase route and tariff	Input per 1M tokens	Output per 1M tokens	Source
Claude Sonnet 5	Anthropic	Direct from developerStandard API	Lowest listed price: $2	Lowest listed price: $10	Source09/22/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/eu-west-1	$2.2	$11	Source10/17/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/global	Lowest listed price: $2	Lowest listed price: $10	Source10/17/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/us-east-1	$2.2	$11	Source10/17/2026
	Anthropic	Via OpenRouteranthropic	Lowest listed price: $2	Lowest listed price: $10	Source10/17/2026
	Azure	Via OpenRouterazure/global	Lowest listed price: $2	Lowest listed price: $10	Source10/17/2026
	Azure	Via OpenRouterazure/us	$2.2	$11	Source10/17/2026
	Claude Platform on AWS	Via OpenRouterclaude-on-aws	Lowest listed price: $2	Lowest listed price: $10	Source10/17/2026
	Google	Via OpenRoutergoogle-vertex/europe	$2.2	$11	Source10/17/2026
	Google	Via OpenRoutergoogle-vertex/global	Lowest listed price: $2	Lowest listed price: $10	Source10/17/2026
	Google	Via OpenRoutergoogle-vertex/us	$2.2	$11	Source10/17/2026
DeepSeek-V4.1-Flash	DeepSeek	Direct from developerStandard API	$0.15	$0.6	Source09/23/2026
	Alibaba	Via OpenRouteralibaba	$0.3	$1.2	Source10/17/2026
	AtlasCloud	Via OpenRouteratlas-cloud/fp8	$0.135	$0.54	Source10/17/2026
	Baidu	Via OpenRouterbaidu/fp8	$0.3	$1.2	Source10/17/2026
	BaseTen	Via OpenRouterbaseten	$0.3	$1.2	Source10/17/2026
	BaseTen	Via OpenRouterbaseten/us	$0.3	$1.2	Source10/17/2026
	Cloudflare	Via OpenRoutercloudflare	$0.1	$0.9	Source10/17/2026
	CoreWeave	Via OpenRoutercoreweave/fp8	$0.15	$0.65	Source10/17/2026
	Crusoe	Via OpenRoutercrusoe/fp8	$0.29	$1.2	Source10/17/2026
	Decart	Via OpenRouterdecart/fp4	$0.09	$0.18	Source10/17/2026
	DeepInfra	Via OpenRouterdeepinfra/fp8	$0.14	$0.42	Source10/17/2026
	DeepInfra	Via OpenRouterdeepinfra/fp8/flex	$0.112	$0.336	Source10/17/2026
	DeepInfra	Via OpenRouterdeepinfra/fp8/priority	$0.21	$0.63	Source10/17/2026
	DeepSeek	Via OpenRouterdeepseek	$0.15	$0.6	Source10/17/2026
	DigitalOcean	Via OpenRouterdigitalocean	$0.195	$0.78	Source10/17/2026
	Fireworks	Via OpenRouterfireworks	$0.3	$1.2	Source10/17/2026
	Fireworks	Via OpenRouterfireworks/us	$0.45	$1.8	Source10/17/2026
	GMICloud	Via OpenRoutergmicloud/fp8	$0.18	$0.72	Source10/17/2026
	InferenceNet	Via OpenRouterinference-net/fp8	$0.103	$0.715	Source10/17/2026
	Ionstream	Via OpenRouterionstream	$0.27	$1.1	Source10/17/2026
	Makora	Via OpenRoutermakora/fp8	$0.27	$1.15	Source10/17/2026
	Modal	Via OpenRoutermodal	$0.3	$1.2	Source10/17/2026
	Morph	Via OpenRoutermorph/fp8	$0.04	$0.7	Source10/17/2026
	Novita	Via OpenRouternovita/fp8	$0.195	$0.78	Source10/17/2026
	OpenInference	Via OpenRouteropen-inference/fp4	Lowest listed price: $0.032	Lowest listed price: $0.144	Source10/17/2026
	Parasail	Via OpenRouterparasail/fp8	$0.3	$1.2	Source10/17/2026
	Phala	Via OpenRouterphala	$0.21	$0.84	Source10/17/2026
	PrimeIntellect	Via OpenRouterprimeintellect	$0.3	$1.2	Source10/17/2026
	Relace	Via OpenRouterrelace	$0.2	$0.6	Source10/17/2026
	Sail Research	Via OpenRoutersail-research/fp4	$0.09	$0.3	Source10/17/2026
	SiliconFlow	Via OpenRoutersiliconflow/fp8	$0.3	$1.2	Source10/17/2026
	StreamLake	Via OpenRouterstreamlake/fp8	$0.1497	$0.5988	Source10/17/2026
	Together	Via OpenRoutertogether	$0.3	$1.2	Source10/17/2026
	Venice	Via OpenRoutervenice/fp8	$0.3	$1.2	Source10/17/2026
	Wafer	Via OpenRouterwafer/mxfp4	$0.1	$0.65	Source10/17/2026

Performance

Shared benchmarks

Only published results with the same benchmark version, task, metric, and comparison cohort are paired. Different reasoning levels, agents, harnesses, or output limits appear directly in the table.

Capability profile from matched benchmarks

Each axis averages directly matched benchmark families. A value of 100 means the stronger value within this pair, not a universal quality score.

Not enough directly matched categories for a reliable radar

Only 0 of at least 5 categories have comparable, direct model measurements. The benchmark tables below show the available evidence without filling missing axes.

Claude Sonnet 5DeepSeek-V4.1-Flash

Code MigrationOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 544.392 %

DeepSeek-V4.1-Flash45.623 %

CyberBench v1.1Overall. Higher is better. Test setup not documented as identical

Claude Sonnet 561.905 %

DeepSeek-V4.1-Flash73.69 %

EMBOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 566.316 %

DeepSeek-V4.1-Flash57.208 %

Finance Agent (v2)Overall. Higher is better. Test setup not documented as identical

Claude Sonnet 553.909 %

DeepSeek-V4.1-Flash53.481 %

Harvey's Legal Agent BenchmarkOverall · Task fully resolved. Higher is better. Test setup not documented as identical

Claude Sonnet 55 %

DeepSeek-V4.1-Flash6.667 %

IOIOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 545 %

DeepSeek-V4.1-Flash40.278 %

Legal Research BenchOverall · All-pass. Higher is better. Test setup not documented as identical

Claude Sonnet 541.827 %

DeepSeek-V4.1-Flash41.346 %

LegalBenchOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 583.922 %

DeepSeek-V4.1-Flash83.277 %

LMArena Code Arena WebDevOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 51,539.919

DeepSeek-V4.1-Flash1,618.513

LMArena Text, Style ControlOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 51,461.284

DeepSeek-V4.1-Flash1,474.579

LMArena Vision, Style ControlOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 51,263.255

DeepSeek-V4.1-Flash1,260.318

MedCodeOverall. Higher is better. Test setup not documented as identical

Claude Sonnet 547.54 %

DeepSeek-V4.1-Flash41.173 %

Key to the marks:better valuebetter, but not conclusivetie

Benchmark scores for Claude Sonnet 5 and DeepSeek-V4.1-Flash
Benchmark and task	Claude Sonnet 5	DeepSeek-V4.1-Flash	Source
Code MigrationOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	44.392 %	Higher measured value45.623 %	Vals AI Source details Data as of: 10/12/2026
CyberBench v1.1Overall Test details Test setup not documented as identicalNo direct winnerVersion: 1.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	61.905 %	Higher measured value73.69 %	Vals AI Source details Data as of: 10/12/2026
EMBOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value66.316 %	57.208 %	Vals AI Source details Data as of: 10/12/2026
Finance Agent (v2)Overall Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value53.909 %	53.481 %	Vals AI Source details Data as of: 10/12/2026
Harvey's Legal Agent BenchmarkOverall · Task fully resolved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: task resolution rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	5 %	Higher measured value6.667 %	Vals AI Source details Data as of: 10/12/2026
IOIOverall Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value45 %	40.278 %	Vals AI Source details Data as of: 10/14/2026
Legal Research BenchOverall · All-pass Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: all-pass rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	Higher measured value41.827 %	41.346 %	Vals AI Source details Data as of: 10/12/2026
LegalBenchOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value83.922 %	83.277 %	Vals AI Source details Data as of: 10/13/2026
LMArena Code Arena WebDevOverall Test details Test setup not documented as identicalNo direct winnerVersion: webdevMetric: WebDev Arena Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Code Arena WebDev DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Code Arena WebDevClaude Sonnet 5: Arena rating from 15,175 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 3,544 published pairwise votes.	1,539.919 95% confidence interval: ±6.061The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	Higher measured value1,618.513 95% confidence interval: ±10.935The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/13/2026
LMArena Text, Style ControlOverall Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Text, style control DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Text, style controlClaude Sonnet 5: Arena rating from 48,998 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 12,000 published pairwise votes.	1,461.284 95% confidence interval: ±4.141The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	Higher measured value1,474.579 95% confidence interval: ±6.317The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/13/2026
LMArena Vision, Style ControlOverall Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Vision, style control DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Vision, style controlClaude Sonnet 5: Arena rating from 13,503 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 3,559 published pairwise votes.	Higher measured value1,263.255 95% confidence interval: ±6.921The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	1,260.318 95% confidence interval: ±10.899The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/09/2026
MedCodeOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 30,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value47.54 %	41.173 %	Vals AI Source details Data as of: 10/13/2026
MedScribeOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 30,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	76.054 %	Higher measured value85.5 %	Vals AI Source details Data as of: 10/13/2026
ProgramBenchOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: fully resolved rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	0 %	Higher measured value0.5 %	Vals AI Source details Data as of: 10/12/2026
ProofBenchOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value77 %	54 %	Vals AI Source details Data as of: 10/12/2026
Public Benefits Bench v1.1Overall Test details Test setup not documented as identicalNo direct winnerVersion: 1.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	Higher measured value66.035 %	64.276 %	Vals AI Source details Data as of: 10/12/2026
SAGEOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 30,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 30,000 tokens	Higher measured value48.925 %	47.88 %	Vals AI Source details Data as of: 10/08/2026
SkillsBenchOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Harness: OpenHands, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Harness: OpenHands, Output limit: 384,000 tokens	46.476 %	Higher measured value69.802 %	Vals AI Source details Data as of: 09/27/2026
SRE BenchOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: fully solved rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	0.382 %	Higher measured value0.763 %	Vals AI Source details Data as of: 10/14/2026
Tax Agent BenchOverall Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	Higher measured value29.374 %	26.63 %	Vals AI Source details Data as of: 10/12/2026
Terminal-Bench 2.1Overall Test details Test setup not documented as identicalNo direct winnerVersion: 2.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	No direct winner74.532 %	No direct winner74.532 %	Vals AI Source details Data as of: 09/28/2026
Terminal-Bench 4.0Overall Test details Test setup not documented as identicalNo direct winnerVersion: 4.0Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	10.606 %	Higher measured value19.697 %	Vals AI Source details Data as of: 10/13/2026
Terminal-Bench ScienceOverall Test details Test setup not documented as identicalNo direct winnerVersion: 0.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Harness: Mini-SWE-agent, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Harness: Mini-SWE-agent, Output limit: 384,000 tokens	Higher measured value5.714 %	0 %	Vals AI Source details Data as of: 10/14/2026
Vals IndexOverall Test details Test setup not documented as identicalNo direct winnerVersion: 2.1Metric: weighted index scoreScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value51.898 %	51.32 %	Vals AI Source details Data as of: 10/13/2026
Vibe Code Bench 1-100Overall Test details Test setup not documented as identicalNo direct winnerVersion: 1.0Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Harness: OpenHands, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Harness: OpenHands, Output limit: 384,000 tokens	13.822 %	Higher measured value16.378 %	Vals AI Source details Data as of: 10/14/2026
Vibe Code Bench v1.1Overall Test details Test setup not documented as identicalNo direct winnerVersion: 1.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Harness: OpenHands, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Harness: OpenHands, Output limit: 384,000 tokens	81.325 %	Higher measured value84.739 %	Vals AI Source details Data as of: 10/12/2026
Code MigrationCLI Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	36.332 %	Higher measured value37.497 %	Vals AI Source details Data as of: 10/12/2026
CyberBench v1.1Patch Test details Test setup not documented as identicalNo direct winnerVersion: 1.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	82.143 %	Higher measured value85.714 %	Vals AI Source details Data as of: 10/12/2026
EMBComps Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value69.384 %	43.925 %	Vals AI Source details Data as of: 10/12/2026
Finance Agent (v2)Adjustments Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	48.715 %	Higher measured value49.241 %	Vals AI Source details Data as of: 10/12/2026
Harvey's Legal Agent BenchmarkAntitrust Competition · Criteria passed Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: criteria pass rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	Higher measured value88.768 %	87.681 %	Vals AI Source details Data as of: 10/12/2026
IOIIOI 2024 Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value50.5 %	42.667 %	Vals AI Source details Data as of: 10/14/2026
Legal Research BenchAdministrative / Regulatory · All-pass Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: all-pass rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	Higher measured value54.545 %	53.03 %	Vals AI Source details Data as of: 10/12/2026
LegalBenchConclusion Tasks Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value89.555 %	89.075 %	Vals AI Source details Data as of: 10/13/2026
LMArena Code Arena WebDevImage to webdev Test details Test setup not documented as identicalNo direct winnerVersion: webdevMetric: WebDev Arena Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Code Arena WebDev DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Code Arena WebDevClaude Sonnet 5: Arena rating from 7,633 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 766 published pairwise votes.	1,539.169 95% confidence interval: ±7.844The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	Higher measured value1,608.867 95% confidence interval: ±22.194The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/09/2026
LMArena Text, Style ControlBusiness, management and finance Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Text, style control DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Text, style controlClaude Sonnet 5: Arena rating from 9,443 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 2,143 published pairwise votes.	1,464.402 95% confidence interval: ±6.971The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	Higher measured value1,476.217 95% confidence interval: ±12.877The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/13/2026
LMArena Vision, Style ControlCreative writing vision Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Vision, style control DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Vision, style controlClaude Sonnet 5: Arena rating from 1,067 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 299 published pairwise votes.	1,236.247 95% confidence interval: ±19.371The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	Higher measured value1,245.252 95% confidence interval: ±36.257The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/09/2026
ProgramBenchAlmost Resolved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: almost-resolved rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	13.5 %	Higher measured value16.5 %	Vals AI Source details Data as of: 10/12/2026
SAGEAutomata Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 30,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 30,000 tokens	Higher measured value34.92 %	32.936 %	Vals AI Source details Data as of: 10/08/2026
SkillsBenchNo Skills Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Harness: OpenHands, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Harness: OpenHands, Output limit: 384,000 tokens	35.123 %	Higher measured value61.658 %	Vals AI Source details Data as of: 09/27/2026
SRE BenchCapability Score Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: capability scoreScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	7.697 %	Higher measured value14.249 %	Vals AI Source details Data as of: 10/14/2026
Tax Agent BenchControversy & Precedence Analysis Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	Higher measured value10 %	3.333 %	Vals AI Source details Data as of: 10/12/2026
Terminal-Bench 2.1Easy Test details Test setup not documented as identicalNo direct winnerVersion: 2.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value100 %	91.667 %	Vals AI Source details Data as of: 09/28/2026
Terminal-Bench 4.0Hardware Test details Test setup not documented as identicalNo direct winnerVersion: 4.0Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	No direct winner0 %	No direct winner0 %	Vals AI Source details Data as of: 10/13/2026
Terminal-Bench ScienceEarth Sciences Test details Test setup not documented as identicalNo direct winnerVersion: 0.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Harness: Mini-SWE-agent, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Harness: Mini-SWE-agent, Output limit: 384,000 tokens	No direct winner0 %	No direct winner0 %	Vals AI Source details Data as of: 10/14/2026
Vals IndexCode Migration Test details Test setup not documented as identicalNo direct winnerVersion: 2.1Metric: benchmark scoreScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	44.089 %	Higher measured value46.854 %	Vals AI Source details Data as of: 10/13/2026
Code MigrationCOBOL Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	68.571 %	Higher measured value70 %	Vals AI Source details Data as of: 10/12/2026
CyberBench v1.1PoC Test details Test setup not documented as identicalNo direct winnerVersion: 1.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	41.667 %	Higher measured value61.667 %	Vals AI Source details Data as of: 10/12/2026
EMBDataroom Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value84.909 %	73.863 %	Vals AI Source details Data as of: 10/12/2026
Finance Agent (v2)All-Pass Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value42.084 %	41.052 %	Vals AI Source details Data as of: 10/12/2026
Harvey's Legal Agent BenchmarkAntitrust Competition · Task fully resolved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: task resolution rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	No direct winner0 %	No direct winner0 %	Vals AI Source details Data as of: 10/12/2026
IOIIOI 2025 Test details Test setup not documented as identicalNo direct winnerVersion: 2Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value42 %	35.167 %	Vals AI Source details Data as of: 10/14/2026
Legal Research BenchAdministrative / Regulatory · Weighted partial credit Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: weighted partial-credit scoreScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	87.81 %	Higher measured value89.06 %	Vals AI Source details Data as of: 10/12/2026
LegalBenchInterpretation Tasks Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value81.412 %	80.448 %	Vals AI Source details Data as of: 10/13/2026
LMArena Code Arena WebDevWebdev Test details Test setup not documented as identicalNo direct winnerVersion: webdevMetric: WebDev Arena Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Code Arena WebDev DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Code Arena WebDevClaude Sonnet 5: Arena rating from 15,175 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 3,544 published pairwise votes.	1,539.919 95% confidence interval: ±6.061The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	Higher measured value1,618.513 95% confidence interval: ±10.935The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/13/2026
LMArena Text, Style ControlChinese Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Text, style control DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Text, style controlClaude Sonnet 5: Arena rating from 3,748 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 918 published pairwise votes.	1,497.538 95% confidence interval: ±10.206The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	Higher measured value1,522.52 95% confidence interval: ±19.943The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/13/2026
LMArena Vision, Style ControlDiagram Test details Test setup not documented as identicalNo direct winnerVersion: style-control-v1Metric: style-controlled Bradley-Terry ratingScoring: Higher is betterClaude Sonnet 5: Snapshot: claude-sonnet-5-high, Reasoning: high, Harness: Arena Vision, style control DeepSeek-V4.1-Flash: Snapshot: deepseek-v4.1-flash-max, Reasoning: max, Harness: Arena Vision, style controlClaude Sonnet 5: Arena rating from 3,582 published pairwise votes.DeepSeek-V4.1-Flash: Arena rating from 955 published pairwise votes.	Higher measured value1,295.106 95% confidence interval: ±10.613The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	1,290.828 95% confidence interval: ±19.74The Arena score measures human preference rather than a fixed capability test. The confidence interval, Arena category, and model configuration are part of the result.	LMArena Source details Data as of: 10/09/2026
ProgramBenchFully Resolved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: fully resolved rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	0 %	Higher measured value0.5 %	Vals AI Source details Data as of: 10/12/2026
SAGELinear Algebra Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 30,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 30,000 tokens	Higher measured value68.999 %	62.29 %	Vals AI Source details Data as of: 10/08/2026
SkillsBenchWith Skills Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Harness: OpenHands, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Harness: OpenHands, Output limit: 384,000 tokens	46.476 %	Higher measured value69.802 %	Vals AI Source details Data as of: 09/27/2026
SRE BenchFully Solved Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: fully solved rateScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	0.382 %	Higher measured value0.763 %	Vals AI Source details Data as of: 10/14/2026
Tax Agent BenchControversy & Precedence Analysis Test details Test setup not documented as identicalNo direct winnerVersion: 1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: max, Temperature: 1, Top P: 1, Output limit: 384,000 tokens	Higher measured value57.41 %	52.802 %	Vals AI Source details Data as of: 10/12/2026
Terminal-Bench 2.1Hard Test details Test setup not documented as identicalNo direct winnerVersion: 2.1Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	Higher measured value57.778 %	56.667 %	Vals AI Source details Data as of: 09/28/2026
Terminal-Bench 4.0Media Test details Test setup not documented as identicalNo direct winnerVersion: 4.0Metric: accuracyScoring: Higher is betterClaude Sonnet 5: Compute: max, Temperature: 1, Output limit: 128,000 tokens DeepSeek-V4.1-Flash: Reasoning: high, Output limit: 384,000 tokens	No direct winner8.333 %	No direct winner8.333 %	Vals AI Source details Data as of: 10/13/2026
Key to the marks:better valuebetter, but not conclusivetie

Our model tests

Our tests

SVG short test

One SVG prompt and fixed output settings. Captures are shown only with 0 reported reasoning tokens or documented lack of reasoning controls. Identical test conditions do not make the models' internal compute identical.

Shared test round: 4ae5d8eeb9a9

Claude Sonnet 5

Unavailable in this round

DeepSeek-V4.1-Flash

Earlier tests

Pelican on a bicycle

A community classic for free-form SVG drawing.

Claude Sonnet 5

Reasoning (requested): high

Current attempt

Run date: Sep 7, 2026
API provider: openrouter
Requested API model: anthropic/claude-sonnet-5
API model reported in response: anthropic/claude-sonnet-5
Reasoning setting: high
Pinned endpoint: Anthropic | anthropic/claude-sonnet-5-20260630
Temperature: Provider default
Token limit including reasoning: 8,192 tokens
Test protocol: community-visual-tests-v1
Technical checks: Passed, not a quality rating
Response time: 47.9 s

Visually reviewed. This individual test does not establish overall model quality.

DeepSeek-V4.1-Flash

The response reached the token limit. No complete recording is available.

Reasoning (requested): high

Current attempt

Run date: Oct 5, 2026
API provider: openrouter
Requested API model: deepseek/deepseek-v4.1-flash
API model reported in response: deepseek/deepseek-v4.1-flash
Reasoning setting: high
Pinned endpoint: DeepSeek | deepseek/deepseek-v4.1-flash-20260910
Temperature: Provider default
Token limit including reasoning: 8,192 tokens
Test protocol: community-visual-tests-v1
Technical checks: Failed
Response time: 25.8 s

Not yet visually reviewed. A successful recording does not confirm correct physics or full compliance with the prompt.

Earlier attempts (2)

Oct 2, 2026API request failedReasoning setting: high
Oct 1, 2026API request failedReasoning setting: high

Prompt and test conditions

Generate an SVG of a pelican riding a bicycle

Token limit including reasoning: 8,192 tokens

Task origin (Simon Willison)

How to read this comparison

Winning one benchmark is not an overall verdict

Your workload, budget, and required context length matter most. A coding benchmark says little about visual understanding or agent performance.

The standard price table uses direct developer rates. The provider comparison labels OpenRouter endpoints, regions, and special tariffs separately.

Every result links to its measurement source and retrieval date. Labels distinguish vendor reports, official benchmark leaderboards, and independent evaluations. Disputed or archived results are excluded.

More matchups

Compare Claude Sonnet 5 and DeepSeek-V4.1-Flash with other leading models using the same data and benchmark logic.

View the complete LLM comparison

Claude Sonnet 5 vs. DeepSeek-V4.1-Flash

Change model selection

General specifications

API pricing compared

Shared benchmarks

Capability profile from matched benchmarks

Our tests

SVG short test

Claude Sonnet 5

DeepSeek-V4.1-Flash

Pelican on a bicycle

Winning one benchmark is not an overall verdict

Related LLM comparisons