Noometry

Model comparison

Claude Opus 4.5 vs Mistral Small 3.1

Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 31.7 on the Noometry Index. Mistral Small 3.1 costs 25× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

Last verified . 22 shared benchmarks.

Claude Opus 4.5 Anthropic

50.5

Rank #47 Confirmed

Mistral Small 3.1 Mistral AI

31.7

Rank #269 Confirmed

Summary

  • They share 22 benchmarks with published results for both. Claude Opus 4.5 scores higher in 8 categories and Mistral Small 3.1 in 1 category; 9 gaps are clear of the uncertainty.
  • The widest gap is in knowledge, where Claude Opus 4.5 leads 56.5 to 22.6.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 86.1% for Claude Opus 4.5 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 $5 / $25 for Claude Opus 4.5.
  • Claude Opus 4.5 accepts more context: 200K tokens versus 128K.
  • Mistral Small 3.1 has downloadable open weights; the other is API-only.

Side by side

Claude Opus 4.5Mistral Small 3.1
ProviderAnthropicMistral AI
Noometry Index50.531.7
Released2025-11-012025-03-17
WeightsProprietaryOpen
Context window200K128K
Max output64K102K
Input $ / M tokens$5$0.35
Output $ / M tokens$25$0.56
Results tracked6928

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Category by category

Coding Claude Opus 4.5 leads

Claude Opus 4.5: 54.8 (#27), Mistral Small 3.1: 38.3 (#179)

BenchmarkClaude Opus 4.5Mistral Small 3.1
LMArena Coding15041309
SWE-bench Verified76.7%—
SWE-bench Verified (bash only)76.8%—
LMArena WebDev1494—
SWE-bench Multilingual70.7%—
GSO26.5%—
WeirdML63.7%—
ALE-Bench1,025—
AlgoTune1.77—

Agentic & Tool Use Not comparable

Claude Opus 4.5: 47.3 (#12), Mistral Small 3.1: —

BenchmarkClaude Opus 4.5Mistral Small 3.1
Terminal-Bench63.1%—
Berkeley Function Calling Leaderboard77.5%—
GDPval45.5%—
Remote Labor Index3.8%—
τ²-bench Airline84%—
τ²-bench Banking24.7%—
τ²-bench Retail79.6%—
τ²-bench Telecom92.3%—
Cybench82%—
DeepResearch Bench54.8%—
OSWorld66.3%—
BALROG43.5%—
LMArena Search1180—
METR Time Horizons75%—
Vending-Bench 24,967—

Reasoning Claude Opus 4.5 leads

Claude Opus 4.5: 42.6 (#51), Mistral Small 3.1: 19.7 (#254)

BenchmarkClaude Opus 4.5Mistral Small 3.1
Chess Puzzles12%1%
LMArena Hard Prompts14761278
Epoch Capabilities Index150.09127.48
ARC-AGI-237.6%—
SimpleBench62%—
Kagi LLM Benchmark80.2%—
NYT Connections (extended)52.5%—
ARC-AGI-180%—
EnigmaEval11.9%—
EBR-Bench14.3%—
Mystery Game Puzzles22%—
DTBench89.9%—
LMCA44.5%—
ForecastBench60.7—

Math Claude Opus 4.5 leads

Claude Opus 4.5: 38.6 (#132), Mistral Small 3.1: 14.7 (#301)

BenchmarkClaude Opus 4.5Mistral Small 3.1
OTIS Mock AIME 2024-202586.1%3.9%
LMArena Math14631262
FrontierMath (Tiers 1-3)34.4%—
FrontierMath Tier 44.9%—
ProofBench36%—
Omni-MATH—24.8%
FrontierMath (Feb 2025 set)20.7%—
FrontierMath Tier 4 (v1)4.2%—

Knowledge Claude Opus 4.5 leads

Claude Opus 4.5: 56.5 (#44), Mistral Small 3.1: 22.6 (#271)

BenchmarkClaude Opus 4.5Mistral Small 3.1
GPQA Diamond86%41.9%
LMArena Expert14871257
Humanity's Last Exam25.2%—
SimpleQA Verified45.7%—
MMLU-Pro—61%
Vectara Hallucination Rate10.9%—
GPQA (HELM)—39.2%

Multimodal Mistral Small 3.1 leads

Claude Opus 4.5: 31.4 (#107), Mistral Small 3.1: 33.2 (#99)

BenchmarkClaude Opus 4.5Mistral Small 3.1
LMArena Vision—1136
GeoBench75%—
VPCT40%—
Furniture Assembly28.3%—
LMArena Document1462—

Multilingual Claude Opus 4.5 leads

Claude Opus 4.5: 54.3 (#47), Mistral Small 3.1: 41.2 (#209)

BenchmarkClaude Opus 4.5Mistral Small 3.1
LMArena Non-English14381255
LMArena Chinese14701253
LMArena French14711273
LMArena German14491266
LMArena Japanese14161208
LMArena Korean14241206
LMArena Russian14471263
LMArena Spanish14581283

Instruction Following Claude Opus 4.5 leads

Claude Opus 4.5: 77.5 (#19), Mistral Small 3.1: 63.6 (#230)

BenchmarkClaude Opus 4.5Mistral Small 3.1
LMArena Instruction Following14781264
IFEval—75%

Long Context Claude Opus 4.5 leads

Claude Opus 4.5: 46.5 (#22), Mistral Small 3.1: 39.5 (#178)

BenchmarkClaude Opus 4.5Mistral Small 3.1
LMArena Longer Query14801299
CL-bench21.1%—

Writing & Preference Claude Opus 4.5 leads

Claude Opus 4.5: 68.1 (#28), Mistral Small 3.1: 37.0 (#259)

BenchmarkClaude Opus 4.5Mistral Small 3.1
LMArena Text14511277
LMArena Creative Writing14451253
EQ-Bench Creative Writing1687761
LMArena Multi-Turn14661270
WildBench—78.8%

Frequently asked questions

Is Claude Opus 4.5 better than Mistral Small 3.1?

Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 31.7 on the Noometry Index. Mistral Small 3.1 costs 25× less per token, which makes it the better buy when Claude Opus 4.5's lead doesn't matter for your workload.

Which is cheaper, Claude Opus 4.5 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 Opus 4.5 lists at $5 and $25.

Is Claude Opus 4.5 or Mistral Small 3.1 better for coding?

Claude Opus 4.5 scores higher on coding benchmarks: 54.8 versus 38.3 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 4.5 does, with 200K tokens against 128K.

How many benchmarks do Claude Opus 4.5 and Mistral Small 3.1 share?

22 benchmarks have published results for both models. Claude Opus 4.5 has 69 scored results on Noometry and Mistral Small 3.1 has 28.

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