Noometry

Model comparison

Claude Sonnet 5.5 vs Mistral Small 3.1

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 31.7 on the Noometry Index. Mistral Small 3.1 costs 10.0× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

Last verified . 16 shared benchmarks.

Claude Sonnet 5.5 Anthropic

61.9

Rank #10 Confirmed

Mistral Small 3.1 Mistral AI

31.7

Rank #269 Confirmed

Summary

  • They share 16 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 9 categories and Mistral Small 3.1 in 0 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 14.7.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 100% for Claude Sonnet 5.5 and 3.9% for Mistral Small 3.1.
  • Mistral Small 3.1 is cheaper at $0.35 / $0.56 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
  • Claude Sonnet 5.5 accepts more context: 1M tokens versus 128K.
  • Mistral Small 3.1 has downloadable open weights; the other is API-only.

Side by side

Claude Sonnet 5.5Mistral Small 3.1
ProviderAnthropicMistral AI
Noometry Index61.931.7
Released2026-09-282025-03-17
WeightsProprietaryOpen
Context window1M128K
Max output128K102K
Input $ / M tokens$2$0.35
Output $ / M tokens$10$0.56
Results tracked3228

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Category by category

Coding Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 67.3 (#6), Mistral Small 3.1: 38.3 (#179)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
LMArena Coding15131309
FrontierCode52.1%—
CursorBench55.5%—
LMArena WebDev1774—
FrontierSWE61.9%—
SciCode61%—
ALE-Bench1,819—

Agentic & Tool Use Not comparable

Claude Sonnet 5.5: 45.0 (#16), Mistral Small 3.1: —

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
APEX-Agents75.5%—

Reasoning Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 54.0 (#28), Mistral Small 3.1: 19.7 (#254)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
LMArena Hard Prompts14951278
Epoch Capabilities Index165.03127.48
NYT Connections (extended)80.5%—
CritPt31.4%—
Chess Puzzles—1%
Mystery Game Puzzles65%—

Math Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 87.9 (#6), Mistral Small 3.1: 14.7 (#301)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
OTIS Mock AIME 2024-2025100%3.9%
LMArena Math15101262
FrontierMath (Tiers 1-3)88.8%—
FrontierMath Tier 480.5%—
ProofBench100%—
Omni-MATH—24.8%
FrontierMath Erdős2.9%—

Knowledge Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 66.0 (#12), Mistral Small 3.1: 22.6 (#271)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
GPQA Diamond95.6%41.9%
LMArena Expert15401257
SimpleQA Verified46.5%—
MMLU-Pro—61%
GPQA (HELM)—39.2%

Multimodal Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 51.5 (#6), Mistral Small 3.1: 33.2 (#99)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
LMArena Vision12891136
Furniture Assembly75%—

Multilingual Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 55.3 (#30), Mistral Small 3.1: 41.2 (#209)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
LMArena Non-English14521255
LMArena Chinese15221253
LMArena Russian14511263
LMArena French—1273
LMArena German—1266
LMArena Japanese—1208
LMArena Korean—1206
LMArena Spanish—1283

Instruction Following Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 78.3 (#11), Mistral Small 3.1: 63.6 (#230)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
LMArena Instruction Following14951264
IFEval—75%

Long Context Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 45.9 (#28), Mistral Small 3.1: 39.5 (#178)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
LMArena Longer Query14981299

Writing & Preference Claude Sonnet 5.5 leads

Claude Sonnet 5.5: 66.0 (#40), Mistral Small 3.1: 37.0 (#259)

BenchmarkClaude Sonnet 5.5Mistral Small 3.1
LMArena Text14711277
LMArena Creative Writing14651253
LMArena Multi-Turn14741270
EQ-Bench Creative Writing—761
WildBench—78.8%

Frequently asked questions

Is Claude Sonnet 5.5 better than Mistral Small 3.1?

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 31.7 on the Noometry Index. Mistral Small 3.1 costs 10.0× less per token, which makes it the better buy when Claude Sonnet 5.5's lead doesn't matter for your workload.

Which is cheaper, Claude Sonnet 5.5 or Mistral Small 3.1?

Mistral Small 3.1 is cheaper. It lists at $0.35 per million input tokens and $0.56 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.

Is Claude Sonnet 5.5 or Mistral Small 3.1 better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 38.3 in the Noometry coding category.

Which has the bigger context window?

Claude Sonnet 5.5 does, with 1M tokens against 128K.

How many benchmarks do Claude Sonnet 5.5 and Mistral Small 3.1 share?

16 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and Mistral Small 3.1 has 28.

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