Noometry

Model comparison

Claude Opus 5.5 vs Mistral Medium 3.5

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 40.2 on the Noometry Index. Mistral Medium 3.5 costs 2.7× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

Last verified . 18 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

Mistral Medium 3.5 Mistral AI

40.2

Rank #152 Confirmed

Summary

  • They share 18 benchmarks with published results for both. Claude Opus 5.5 scores higher in 9 categories and Mistral Medium 3.5 in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in reasoning, where Claude Opus 5.5 leads 80.2 to 17.3.
  • The biggest single-benchmark swing is NYT Connections (extended): 88.5% for Claude Opus 5.5 and 12.9% for Mistral Medium 3.5.
  • Mistral Medium 3.5 is cheaper at $1.50 / $7.50 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
  • Claude Opus 5.5 accepts more context: 1M tokens versus 262K.
  • Mistral Medium 3.5 has downloadable open weights; the other is API-only.

Side by side

Claude Opus 5.5Mistral Medium 3.5
ProviderAnthropicMistral AI
Noometry Index68.640.2
Released2026-09-22—
WeightsProprietaryOpen
Context window1M262K
Max output128K210K
Input $ / M tokens$4$1.50
Output $ / M tokens$20$7.50
Results tracked4422

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Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), Mistral Medium 3.5: 36.0 (#213)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena WebDev18131264
LMArena Coding15471461
FrontierCode54.6%—
CursorBench57.8%—
FrontierSWE62.3%—
SciCode66.9%—
MirrorCode77.4%—
ALE-Bench2,147—

Agentic & Tool Use Not comparable

Claude Opus 5.5: 45.3 (#15), Mistral Medium 3.5: —

BenchmarkClaude Opus 5.5Mistral Medium 3.5
APEX-Agents73.5%—
GDP.pdf30.6%—
Vending-Bench 29,235—

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), Mistral Medium 3.5: 17.3 (#295)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
NYT Connections (extended)88.5%12.9%
LMArena Hard Prompts15351436
Epoch Capabilities Index167.33141.35
ARC-AGI-293.3%—
Kagi LLM Benchmark—41.4%
ARC-AGI-198.5%—
CritPt31.7%—
EBR-Bench71.4%—
Mystery Game Puzzles71%—
DTBench98.9%—
LMCA68.2%—

Math Claude Opus 5.5 leads

Claude Opus 5.5: 91.8 (#3), Mistral Medium 3.5: 39.1 (#113)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena Math15061431
FrontierMath (Tiers 1-3)91.2%—
FrontierMath Tier 495%—
OTIS Mock AIME 2024-2025100%—
ProofBench100%—
FrontierMath Erdős2.9%—

Knowledge Claude Opus 5.5 leads

Claude Opus 5.5: 66.4 (#10), Mistral Medium 3.5: 40.0 (#126)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena Expert15471432
GPQA Diamond90.6%—
SimpleQA Verified72.2%—

Multimodal Claude Opus 5.5 leads

Claude Opus 5.5: 57.8 (#1), Mistral Medium 3.5: 38.3 (#65)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena Vision13211223
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—

Multilingual Claude Opus 5.5 leads

Claude Opus 5.5: 59.1 (#2), Mistral Medium 3.5: 51.9 (#100)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena Non-English15071404
LMArena Chinese15881442
LMArena French15141448
LMArena Russian15201395
LMArena Spanish15071409
LMArena German—1451
LMArena Korean—1385

Instruction Following Claude Opus 5.5 leads

Claude Opus 5.5: 80.0 (#3), Mistral Medium 3.5: 74.6 (#90)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena Instruction Following15371415

Long Context Claude Opus 5.5 leads

Claude Opus 5.5: 47.1 (#19), Mistral Medium 3.5: 43.2 (#103)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena Longer Query15321415

Writing & Preference Claude Opus 5.5 leads

Claude Opus 5.5: 78.2 (#3), Mistral Medium 3.5: 58.5 (#117)

BenchmarkClaude Opus 5.5Mistral Medium 3.5
LMArena Text15151421
LMArena Creative Writing15331374
LMArena Multi-Turn14991423
EQ-Bench Creative Writing2050—
EQ-Bench 4—993

Frequently asked questions

Is Claude Opus 5.5 better than Mistral Medium 3.5?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 40.2 on the Noometry Index. Mistral Medium 3.5 costs 2.7× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

Which is cheaper, Claude Opus 5.5 or Mistral Medium 3.5?

Mistral Medium 3.5 is cheaper. It lists at $1.50 per million input tokens and $7.50 per million output tokens; Claude Opus 5.5 lists at $4 and $20.

Is Claude Opus 5.5 or Mistral Medium 3.5 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 36.0 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 5.5 does, with 1M tokens against 262K.

How many benchmarks do Claude Opus 5.5 and Mistral Medium 3.5 share?

18 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Mistral Medium 3.5 has 22.

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