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Head-to-head comparison

Claude Opus 5.5 vs. Mistral Medium 3.5

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

shared result series
12
distinct benchmarks
12
latest retrieval
2026-09-23

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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 Opus 5.5 and Mistral Medium 3.5
AttributeClaude Opus 5.5Mistral Medium 3.5
ProviderAnthropicMistral AI
ReleasedSep 22, 2026Apr 28, 2026
AvailabilityActiveActive
Model typeProprietaryOpen Weights
ParametersNot published128B
ArchitectureNot publishedDense
Context window1,000,000 tokens262,144 tokens
Knowledge cutoffJune 2026Not published
Technical sourcesModelModel, Context

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 Opus 5.5 and Mistral Medium 3.5
Price typeClaude Opus 5.5Mistral Medium 3.5
API input$4$1.5
API output$20$7.5
Cache read$0.2Not listed
Cache write (5 min.)$5Not listed
Cache write (1 hr.)$8Not listed
Price verified09/22/2026 Source09/22/2026 Source
Claude Opus 5.5Mistral Medium 3.5
API inputUSD per 1M tokens, base tier
Claude Opus 5.5$4
Mistral Medium 3.5Lower price$1.5
API outputUSD per 1M tokens, base tier
Claude Opus 5.5$20
Mistral Medium 3.5Lower price$7.5

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 Opus 5.5 and Mistral Medium 3.5
ModelProviderPurchase route and tariffInput per 1M tokensOutput per 1M tokensSource
Claude Opus 5.5AnthropicDirect from developerStandard APILowest listed price: $4Lowest listed price: $20Source09/22/2026
Amazon BedrockVia OpenRouteramazon-bedrockLowest listed price: $4Lowest listed price: $20Source09/23/2026
Amazon BedrockVia OpenRouteramazon-bedrock/eu-west-1$4.4$22Source09/23/2026
Amazon BedrockVia OpenRouteramazon-bedrock/us-east-1$4.4$22Source09/23/2026
AnthropicVia OpenRouteranthropicLowest listed price: $4Lowest listed price: $20Source09/23/2026
AnthropicVia OpenRouteranthropic/fast$8$40Source09/23/2026
AzureVia OpenRouterazure/globalLowest listed price: $4Lowest listed price: $20Source09/23/2026
AzureVia OpenRouterazure/us$4.4$22Source09/23/2026
Claude Platform on AWSVia OpenRouterclaude-on-awsLowest listed price: $4Lowest listed price: $20Source09/23/2026
GoogleVia OpenRoutergoogle-vertex/europe$4.4$22Source09/23/2026
GoogleVia OpenRoutergoogle-vertex/globalLowest listed price: $4Lowest listed price: $20Source09/23/2026
GoogleVia OpenRoutergoogle-vertex/us$4.4$22Source09/23/2026
Mistral Medium 3.5Mistral AIDirect from developerStandard APILowest listed price: $1.5Lowest listed price: $7.5Source09/22/2026
MistralVia OpenRoutermistralLowest listed price: $1.5Lowest listed price: $7.5Source09/23/2026
MistralVia OpenRoutermistral/zdrLowest listed price: $1.5Lowest listed price: $7.5Source09/23/2026

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.

255075100CodingMathematicsFinanceLegalAgentic tasksHealthEducationOverall
Claude Opus 5.5
Mistral Medium 3.5
Coding: 100 / 5.4 (2 benchmark families)
Mathematics: 100 / 9 (1 benchmark family)
Finance: 100 / 34.8 (2 benchmark families)
Legal: 100 / 14.6 (2 benchmark families)
Agentic tasks: 100 / 44.4 (1 benchmark family)
Health: 100 / 70.9 (2 benchmark families)
Education: 100 / 82.1 (1 benchmark family)
Overall: 100 / 25.8 (1 benchmark family)

12 matched rows from 12 benchmark families were considered. The radar shows 8 of 8 comparable categories.

Claude Opus 5.5Mistral Medium 3.5
Code MigrationOverall. Higher is better. No documented setup difference
Claude Opus 5.5Winner66.646 %
Mistral Medium 3.55.127 %
EMBOverall. Higher is better. No documented setup difference
Claude Opus 5.5Winner75.938 %
Mistral Medium 3.511.185 %
Finance Agent (v2)Overall. Higher is better. No documented setup difference
Claude Opus 5.5Winner58.587 %
Mistral Medium 3.532.103 %
Harvey's Legal Agent BenchmarkOverall · Task fully resolved. Higher is better. No documented setup difference
Claude Opus 5.5Winner3.75 %
Mistral Medium 3.50.417 %
Legal Research BenchOverall · All-pass. Higher is better. No documented setup difference
Claude Opus 5.5Winner50.481 %
Mistral Medium 3.59.135 %
MedCodeOverall. Higher is better. No documented setup difference
Claude Opus 5.5Winner49.797 %
Mistral Medium 3.533.752 %
MedScribeOverall. Higher is better. No documented setup difference
Claude Opus 5.5Winner91.43 %
Mistral Medium 3.567.728 %
ProofBenchOverall. Higher is better. No documented setup difference
Claude Opus 5.5Winner100 %
Mistral Medium 3.59 %
SAGEOverall. Higher is better. No documented setup difference
Claude Opus 5.5Winner45.831 %
Mistral Medium 3.537.613 %
Terminal-Bench 2.1Overall. Higher is better. No documented setup difference
Claude Opus 5.5Winner87.64 %
Mistral Medium 3.538.951 %
Vals IndexOverall. Higher is better. No documented setup difference
Claude Opus 5.5Winner69.689 %
Mistral Medium 3.517.947 %
Vibe Code Bench v1.1Overall. Higher is better. No documented setup difference
Claude Opus 5.5Winner90.294 %
Mistral Medium 3.52.888 %

Key to the marks:better valuebetter, but not conclusivetie

Benchmark scores for Claude Opus 5.5 and Mistral Medium 3.5
Benchmark and taskClaude Opus 5.5Mistral Medium 3.5Source
Code MigrationOverall
Test details
No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better
Winner66.646 %
5.127 %
Vals AI
Source details
Data as of: 09/22/2026
EMBOverall
Test details
No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better
Winner75.938 %
11.185 %
Vals AI
Source details
Data as of: 09/22/2026
Finance Agent (v2)Overall
Test details
No documented difference in the test setupVersion: 2Metric: accuracyScoring: Higher is better
Winner58.587 %
32.103 %
Vals AI
Source details
Data as of: 09/22/2026
Harvey's Legal Agent BenchmarkOverall · Task fully resolved
Test details
No documented difference in the test setupVersion: 1Metric: task resolution rateScoring: Higher is better
Winner3.75 %
0.417 %
Vals AI
Source details
Data as of: 09/22/2026
Legal Research BenchOverall · All-pass
Test details
No documented difference in the test setupVersion: 1Metric: all-pass rateScoring: Higher is better
Winner50.481 %
9.135 %
Vals AI
Source details
Data as of: 09/22/2026
MedCodeOverall
Test details
No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better
Winner49.797 %
33.752 %
Vals AI
Source details
Data as of: 09/22/2026
MedScribeOverall
Test details
No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better
Winner91.43 %
67.728 %
Vals AI
Source details
Data as of: 09/22/2026
ProofBenchOverall
Test details
No documented difference in the test setupVersion: 1.1Metric: accuracyScoring: Higher is better
Winner100 %
9 %
Vals AI
Source details
Data as of: 09/22/2026
SAGEOverall
Test details
No documented difference in the test setupVersion: 1Metric: accuracyScoring: Higher is better
Winner45.831 %
37.613 %
Vals AI
Source details
Data as of: 09/22/2026
Terminal-Bench 2.1Overall
Test details
No documented difference in the test setupVersion: 2.1Metric: accuracyScoring: Higher is better
Winner87.64 %
38.951 %
Vals AI
Source details
Data as of: 09/22/2026
Vals IndexOverall
Test details
No documented difference in the test setupVersion: 2Metric: weighted index scoreScoring: Higher is better
Winner69.689 %
17.947 %
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
Winner90.294 %
2.888 %
Vals AI
Source details
Data as of: 09/22/2026

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 first attempt, with no subsequent fixes to the generated code. These results do not contribute to an overall score.

Pelican on a bicycle

A community classic for free-form SVG drawing.

Claude Opus 5.5

Not tested yet

Mistral Medium 3.5

API access was unavailable for this run. The model was not evaluated.

Reasoning (requested): high

First attempt
Run date
7 Sept 2026
API provider
openrouter
Requested API model
mistralai/mistral-medium-3-5
Reasoning setting
high
Pinned endpoint
Mistral | mistralai/mistral-medium-3.5-20260430
Temperature
Provider default
Token limit including reasoning
8,192 tokens
Test protocol
community-visual-tests-v1
Technical checks
Not run

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

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

Related LLM comparisons

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View the complete LLM comparison