Head-to-head comparison

GPT-5.6 Terra 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: 21
distinct benchmarks: 21
latest retrieval: 2026-09-29

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 GPT-5.6 Terra and DeepSeek-V4.1-Flash
Attribute	GPT-5.6 Terra	DeepSeek-V4.1-Flash
Provider	OpenAI	DeepSeek
Released	Jul 9, 2026	Sep 10, 2026
Availability	Active	Active
Model type	Proprietary	Open Weights
Parameters	Not published	552B
Architecture	Not published	Mixture of Experts
Context window	1,050,000 tokens	1,000,000 tokens
Knowledge cutoff	February 16, 2026	Not published
Technical sources	Model, Context, Knowledge cutoff	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 GPT-5.6 Terra and DeepSeek-V4.1-Flash
Price type	GPT-5.6 Terra	DeepSeek-V4.1-Flash
API input	$2 ≤272K / $4 >272K	$0.15 (Off-Peak)
API output	$12 ≤272K / $18 >272K	$0.6 (Off-Peak)
Cache read	$0.2 ≤272K / $0.4 >272K	$0. (Off-Peak)
Cache write (5 min.)	$2.5 ≤272K / $5 >272K	Not listed
Cache write (1 hr.)	Not listed	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.

GPT-5.6 TerraDeepSeek-V4.1-Flash

API inputUSD per 1M tokens, base tier

GPT-5.6 Terra$2

DeepSeek-V4.1-Flash$0.15

API outputUSD per 1M tokens, base tier

GPT-5.6 Terra$12

DeepSeek-V4.1-Flash$0.6

Cache readUSD per 1M tokens, base tier

GPT-5.6 Terra$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 GPT-5.6 Terra and DeepSeek-V4.1-Flash
Model	Provider	Purchase route and tariff	Input per 1M tokens	Output per 1M tokens	Source
GPT-5.6 Terra	OpenAI	Direct from developerUp to 272,000 context tokens	$2	$12	Source09/22/2026
	OpenAI	Direct from developerAbove 272,000 context tokens	$4	$18	Source09/22/2026
	Amazon Bedrock	Via OpenRouteramazon-bedrock/us-east-1	$2.2	$13.2	Source10/06/2026
	Azure	Via OpenRouterazure	$2	$12	Source10/06/2026
	Azure	Via OpenRouterazure/eu	$2.2	$13.2	Source10/06/2026
	Azure	Via OpenRouterazure/us	$2.2	$13.2	Source10/06/2026
	OpenAI	Via OpenRouteropenai	$2	$12	Source10/06/2026
	OpenAI	Via OpenRouteropenai/fast	$4	$24	Source10/06/2026
	OpenAI	Via OpenRouteropenai/flex	Lowest listed price: $1	Lowest listed price: $6	Source10/06/2026
DeepSeek-V4.1-Flash	DeepSeek	Direct from developerStandard API	$0.15	$0.6	Source09/23/2026
	Alibaba	Via OpenRouteralibaba	$0.15	$0.6	Source10/06/2026
	AtlasCloud	Via OpenRouteratlas-cloud/fp8	$0.141	$0.564	Source10/06/2026
	Baidu	Via OpenRouterbaidu/fp8	$0.3	$1.2	Source10/06/2026
	BaseTen	Via OpenRouterbaseten/fp8#1	$0.3	$1.2	Source10/06/2026
	BaseTen	Via OpenRouterbaseten/fp8#2	$0.3	$1.2	Source10/06/2026
	CoreWeave	Via OpenRoutercoreweave/fp8	$0.2	$0.65	Source10/06/2026
	Decart	Via OpenRouterdecart/fp4	$0.09	Lowest listed price: $0.18	Source10/06/2026
	DeepInfra	Via OpenRouterdeepinfra/fp8	$0.14	$0.42	Source10/06/2026
	DeepSeek	Via OpenRouterdeepseek	$0.15	$0.6	Source10/06/2026
	DekaLLM	Via OpenRouterdekallm	$0.12	$2.4	Source10/06/2026
	DigitalOcean	Via OpenRouterdigitalocean	$0.18	$0.72	Source10/06/2026
	Fireworks	Via OpenRouterfireworks	$0.3	$1.2	Source10/06/2026
	Fireworks	Via OpenRouterfireworks/us	$0.45	$1.8	Source10/06/2026
	GMICloud	Via OpenRoutergmicloud/fp8	$0.18	$0.72	Source10/06/2026
	InferenceNet	Via OpenRouterinference-net	$0.07	$0.3	Source10/06/2026
	Ionstream	Via OpenRouterionstream	$0.1386	$1.175	Source10/06/2026
	Makora	Via OpenRoutermakora/fp8	$0.27	$1.15	Source10/06/2026
	Modal	Via OpenRoutermodal	$0.3	$1.2	Source10/06/2026
	Morph	Via OpenRoutermorph/fp8	$0.033	$0.284	Source10/06/2026
	NextBit	Via OpenRouternextbit/fp8	$0.21	$0.84	Source10/06/2026
	Novita	Via OpenRouternovita/fp8	$0.24	$0.96	Source10/06/2026
	Parasail	Via OpenRouterparasail/fp8	$0.3	$1.2	Source10/06/2026
	Phala	Via OpenRouterphala	$0.21	$0.84	Source10/06/2026
	Relace	Via OpenRouterrelace	Lowest listed price: $0.003	$2.4	Source10/06/2026
	Sail Research	Via OpenRoutersail-research/fp4	$0.08	$0.4	Source10/06/2026
	SiliconFlow	Via OpenRoutersiliconflow/fp8	$0.3	$1.2	Source10/06/2026
	StreamLake	Via OpenRouterstreamlake/fp8	$0.141	$0.564	Source10/06/2026
	Together	Via OpenRoutertogether	$0.3	$1.2	Source10/06/2026
	Venice	Via OpenRoutervenice/fp8	$0.3	$1.2	Source10/06/2026
	Wafer	Via OpenRouterwafer	$0.075	$1.2	Source10/06/2026

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.

GPT-5.6 Terra

DeepSeek-V4.1-Flash

Coding: 95.7 / 77.1 (5 benchmark families)

Mathematics: 100 / 73 (1 benchmark family)

Finance: 100 / 93.5 (3 benchmark families)

Legal: 70.8 / 99.3 (3 benchmark families)

Agentic tasks: 92.2 / 98.1 (2 benchmark families)

Productivity: 97.1 / 100 (1 benchmark family)

Cybersecurity: 97.8 / 100 (1 benchmark family)

Health: 98.5 / 97.4 (2 benchmark families)

21 matched rows from 20 benchmark families were considered. The radar shows 8 of 11 comparable categories.

GPT-5.6 TerraDeepSeek-V4.1-Flash

Code MigrationOverall. Higher is better. No documented setup difference

GPT-5.6 Terra47.804 %

DeepSeek-V4.1-Flash45.623 %

CyberBench v1.1Overall. Higher is better. No documented setup difference

GPT-5.6 Terra72.084 %

DeepSeek-V4.1-Flash73.69 %

EMBOverall. Higher is better. No documented setup difference

GPT-5.6 Terra66.205 %

DeepSeek-V4.1-Flash57.208 %

Finance Agent (v2)Overall. Higher is better. No documented setup difference

GPT-5.6 Terra54.436 %

DeepSeek-V4.1-Flash53.481 %

Harvey's Legal Agent BenchmarkOverall · Task fully resolved. Higher is better. No documented setup difference

GPT-5.6 Terra0.833 %

DeepSeek-V4.1-Flash6.667 %

IOIOverall. Higher is better. No documented setup difference

GPT-5.6 Terra87.611 %

DeepSeek-V4.1-Flash40.278 %

Legal Research BenchOverall · All-pass. Higher is better. No documented setup difference

GPT-5.6 Terra41.346 %

DeepSeek-V4.1-Flash41.346 %

LegalBenchOverall. Higher is better. No documented setup difference

GPT-5.6 Terra85.105 %

DeepSeek-V4.1-Flash83.277 %

MedCodeOverall. Higher is better. No documented setup difference

GPT-5.6 Terra43.414 %

DeepSeek-V4.1-Flash41.173 %

MedScribeOverall. Higher is better. No documented setup difference

GPT-5.6 Terra82.869 %

DeepSeek-V4.1-Flash85.5 %

ProofBenchOverall. Higher is better. No documented setup difference

GPT-5.6 Terra74 %

DeepSeek-V4.1-Flash54 %

Public Benefits Bench v1.1Overall. Higher is better. No documented setup difference

GPT-5.6 Terra62.382 %

DeepSeek-V4.1-Flash64.276 %

Key to the marks:better valuebetter, but not conclusivetie

Benchmark scores for GPT-5.6 Terra and DeepSeek-V4.1-Flash
Benchmark and task	GPT-5.6 Terra	DeepSeek-V4.1-Flash	Source
Code MigrationOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner47.804 %	45.623 %	Vals AI Source details Data as of: 09/27/2026
CyberBench v1.1Overall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is better	72.084 %	Winner73.69 %	Vals AI Source details Data as of: 09/27/2026
EMBOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner66.205 %	57.208 %	Vals AI Source details Data as of: 09/27/2026
Finance Agent (v2)Overall Test details No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better	Winner54.436 %	53.481 %	Vals AI Source details Data as of: 09/27/2026
Harvey's Legal Agent BenchmarkOverall · Task fully resolved Test details No documented difference in the test setupVersion: 1Metric: task resolution rateScoring: Higher is better	0.833 %	Winner6.667 %	Vals AI Source details Data as of: 09/27/2026
IOIOverall Test details No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better	Winner87.611 %	40.278 %	Vals AI Source details Data as of: 09/27/2026
Legal Research BenchOverall · All-pass Test details No documented difference in the test setupVersion: 1Metric: all-pass rateScoring: Higher is better	Tie41.346 %	Tie41.346 %	Vals AI Source details Data as of: 09/27/2026
LegalBenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner85.105 %	83.277 %	Vals AI Source details Data as of: 09/27/2026
MedCodeOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner43.414 %	41.173 %	Vals AI Source details Data as of: 09/26/2026
MedScribeOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	82.869 %	Winner85.5 %	Vals AI Source details Data as of: 09/26/2026
ProofBenchOverall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is better	Winner74 %	54 %	Vals AI Source details Data as of: 09/28/2026
Public Benefits Bench v1.1Overall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is better	62.382 %	Winner64.276 %	Vals AI Source details Data as of: 09/27/2026
SAGEOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	47.003 %	Winner47.88 %	Vals AI Source details Data as of: 09/26/2026
SkillsBenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is betterSettings: Harness: OpenHands	58.895 %	Winner69.802 %	Vals AI Source details Data as of: 09/27/2026
Tax Agent BenchOverall Test details No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better	Winner65.199 %	62.458 %	Vals AI Source details Data as of: 09/27/2026
Terminal-Bench 2.1Overall Test details No documented difference in the test setupVersion: 2.1Metric: accuracyScoring: Higher is better	Winner77.528 %	74.532 %	Vals AI Source details Data as of: 09/27/2026
Terminal-Bench 4.0Overall Test details No documented difference in the test setupVersion: 4.0Metric: accuracyScoring: Higher is better	Winner26.263 %	11.616 %	Vals AI Source details Data as of: 09/27/2026
Terminal-Bench ScienceOverall Test details No documented difference in the test setupVersion: 0.1Metric: accuracyScoring: Higher is better	Winner10 %	4.286 %	Vals AI Source details Data as of: 09/27/2026
Vals IndexOverall Test details No documented difference in the test setupVersion: 2Metric: weighted index scoreScoring: Higher is better	Winner59.588 %	57.86 %	Vals AI Source details Data as of: 09/27/2026
Vibe Code Bench 1-100Overall Test details No documented difference in the test setupVersion: 1.0Metric: accuracyScoring: Higher is betterSettings: Harness: OpenHands	14.822 %	Winner16.378 %	Vals AI Source details Data as of: 09/22/2026
Vibe Code Bench v1.1Overall Test details No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is betterSettings: Harness: OpenHands	74.594 %	Winner84.739 %	Vals AI Source details Data as of: 09/27/2026
Key to the marks:better valuebetter, but not conclusivetie

Our model tests

Our tests

Compare how the models respond to the same prompt. Each test shows the latest attempt, with no subsequent fixes to the generated code. Earlier runs remain available in the test details. These results do not contribute to an overall score.

Pelican on a bicycle

A community classic for free-form SVG drawing.

GPT-5.6 Terra

Reasoning (requested): high

Current attempt

Run date: 7 Sept 2026
API provider: openrouter
Requested API model: openai/gpt-5.6-terra
API model reported in response: openai/gpt-5.6-terra
Reasoning setting: high
Pinned endpoint: OpenAI | openai/gpt-5.6-terra-20260709
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: 64.6 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: 2 Oct 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: 30.5 s

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

Earlier attempts (1)

1 Oct 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 GPT-5.6 Terra and DeepSeek-V4.1-Flash with other leading models using the same data and benchmark logic.

View the complete LLM comparison