Noometry

Model comparison

Claude Opus 5.5 vs Mistral Small 3

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 31.2 on the Noometry Index. Mistral Small 3 costs 139× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

Last verified . 17 shared benchmarks.

Claude Opus 5.5 Anthropic

68.6

Rank #3 Confirmed

Mistral Small 3 Mistral AI

31.2

Rank #278 Confirmed

Summary

  • They share 17 benchmarks with published results for both. Claude Opus 5.5 scores higher in 8 categories and Mistral Small 3 in 0 categories; 8 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Opus 5.5 leads 91.8 to 16.3.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 100% for Claude Opus 5.5 and 6.7% for Mistral Small 3.
  • Mistral Small 3 is cheaper at $0.05 / $0.08 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
  • Claude Opus 5.5 accepts more context: 1M tokens versus 33K.
  • Mistral Small 3 has downloadable open weights; the other is API-only.

Side by side

Claude Opus 5.5Mistral Small 3
ProviderAnthropicMistral AI
Noometry Index68.631.2
Released2026-09-222025-01-30
WeightsProprietaryOpen
Context window1M33K
Max output128K16K
Input $ / M tokens$4$0.05
Output $ / M tokens$20$0.08
Results tracked4424

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Category by category

Coding Claude Opus 5.5 leads

Claude Opus 5.5: 71.9 (#3), Mistral Small 3: 36.5 (#207)

BenchmarkClaude Opus 5.5Mistral Small 3
LMArena Coding15471246
FrontierCode54.6%—
CursorBench57.8%—
LMArena WebDev1813—
FrontierSWE62.3%—
SciCode66.9%—
BigCodeBench Instruct—45.3%
MirrorCode77.4%—
BigCodeBench Complete—50.4%
ALE-Bench2,147—

Agentic & Tool Use Not comparable

Claude Opus 5.5: 45.3 (#15), Mistral Small 3: —

BenchmarkClaude Opus 5.5Mistral Small 3
APEX-Agents73.5%—
GDP.pdf30.6%—
Vending-Bench 29,235—

Reasoning Claude Opus 5.5 leads

Claude Opus 5.5: 80.2 (#3), Mistral Small 3: 18.9 (#273)

BenchmarkClaude Opus 5.5Mistral Small 3
LMArena Hard Prompts15351233
Epoch Capabilities Index167.33127.07
ARC-AGI-293.3%—
NYT Connections (extended)88.5%—
ARC-AGI-198.5%—
CritPt31.7%—
Chess Puzzles—0%
EBR-Bench71.4%—
Mystery Game Puzzles71%—
DTBench98.9%—
LMCA68.2%—

Math Claude Opus 5.5 leads

Claude Opus 5.5: 91.8 (#3), Mistral Small 3: 16.3 (#295)

BenchmarkClaude Opus 5.5Mistral Small 3
OTIS Mock AIME 2024-2025100%6.7%
LMArena Math15061240
FrontierMath (Tiers 1-3)91.2%—
FrontierMath Tier 495%—
ProofBench100%—
FrontierMath Erdős2.9%—

Knowledge Claude Opus 5.5 leads

Claude Opus 5.5: 66.4 (#10), Mistral Small 3: 25.1 (#263)

BenchmarkClaude Opus 5.5Mistral Small 3
GPQA Diamond90.6%47.3%
LMArena Expert15471202
SimpleQA Verified72.2%—
Confabulations—25.2%

Multimodal Not comparable

Claude Opus 5.5: 57.8 (#1), Mistral Small 3: —

BenchmarkClaude Opus 5.5Mistral Small 3
LMArena Vision1321—
Blueprint-Bench 251.2%—
Furniture Assembly83.3%—

Multilingual Claude Opus 5.5 leads

Claude Opus 5.5: 59.1 (#2), Mistral Small 3: 37.3 (#236)

BenchmarkClaude Opus 5.5Mistral Small 3
LMArena Non-English15071198
LMArena Chinese15881204
LMArena French15141203
LMArena Russian15201216
LMArena German—1211
LMArena Japanese—1111
LMArena Korean—1188
LMArena Spanish1507—

Instruction Following Claude Opus 5.5 leads

Claude Opus 5.5: 80.0 (#3), Mistral Small 3: 63.7 (#229)

BenchmarkClaude Opus 5.5Mistral Small 3
LMArena Instruction Following15371214

Long Context Claude Opus 5.5 leads

Claude Opus 5.5: 47.1 (#19), Mistral Small 3: 37.8 (#211)

BenchmarkClaude Opus 5.5Mistral Small 3
LMArena Longer Query15321246

Writing & Preference Claude Opus 5.5 leads

Claude Opus 5.5: 78.2 (#3), Mistral Small 3: 32.2 (#280)

BenchmarkClaude Opus 5.5Mistral Small 3
LMArena Text15151234
LMArena Creative Writing15331195
EQ-Bench Creative Writing2050707
LMArena Multi-Turn14991217

Frequently asked questions

Is Claude Opus 5.5 better than Mistral Small 3?

Claude Opus 5.5 is the stronger model overall, scoring 68.6 to 31.2 on the Noometry Index. Mistral Small 3 costs 139× 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 Small 3?

Mistral Small 3 is cheaper. It lists at $0.05 per million input tokens and $0.08 per million output tokens; Claude Opus 5.5 lists at $4 and $20.

Is Claude Opus 5.5 or Mistral Small 3 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.9 versus 36.5 in the Noometry coding category.

Which has the bigger context window?

Claude Opus 5.5 does, with 1M tokens against 33K.

How many benchmarks do Claude Opus 5.5 and Mistral Small 3 share?

17 benchmarks have published results for both models. Claude Opus 5.5 has 44 scored results on Noometry and Mistral Small 3 has 24.

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