Model comparison

gpt-oss-120b vs Mistral Small 3.1

gpt-oss-120b is the stronger model overall, scoring 36.3 to 31.7 on the Noometry Index.

Last verified . 27 shared benchmarks.

gpt-oss-120b OpenAI

36.3

Rank #217 Confirmed

Mistral Small 3.1 Mistral AI

31.7

Rank #269 Confirmed

Summary

  • They share 27 benchmarks with published results for both. gpt-oss-120b scores higher in 6 categories and Mistral Small 3.1 in 2 categories; 7 gaps are clear of the uncertainty.
  • The widest gap is in math, where gpt-oss-120b leads 52.5 to 14.7.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 88.9% for gpt-oss-120b and 3.9% for Mistral Small 3.1.
  • gpt-oss-120b is cheaper at $0.037 / $0.17 per million input/output tokens, against $0.35 / $0.56 for Mistral Small 3.1.
  • gpt-oss-120b accepts more context: 131K tokens versus 128K.

Side by side

gpt-oss-120b and Mistral Small 3.1 specifications
gpt-oss-120bMistral Small 3.1
ProviderOpenAIMistral AI
Noometry Index36.331.7
Released2025-08-052025-03-17
WeightsOpenOpen
Context window131K128K
Max output41K102K
Input $ / M tokens$0.037$0.35
Output $ / M tokens$0.17$0.56
Results tracked4828

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Category by category

Coding Mistral Small 3.1 leads

gpt-oss-120b: 33.5 (#256), Mistral Small 3.1: 38.3 (#179)

Coding benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
LMArena Coding13801309
SWE-bench Verified (bash only)26%—
Aider Polyglot41.8%—
SciCode36%—
WeirdML48.2%—
ALE-Bench575.62—
AlgoTune1.41—

Agentic & Tool Use Not comparable

gpt-oss-120b: 12.2 (#153), Mistral Small 3.1: —

Agentic & Tool Use benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
Terminal-Bench18.7%—
APEX-Agents4.4%—
METR Time Horizons56.6%—
Vending-Bench 2-21.53—

Reasoning Too close to call

gpt-oss-120b: 20.0 (#245), Mistral Small 3.1: 19.7 (#254)

Reasoning benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
Chess Puzzles20%1%
LMArena Hard Prompts13641278
Epoch Capabilities Index139.93127.48
SimpleBench22.1%—
Kagi LLM Benchmark58.6%—
CritPt1.1%—
Mystery Game Puzzles2%—
DTBench76.3%—
LMCA22.1%—
Surface Evolver Bench25%—

Math gpt-oss-120b leads

gpt-oss-120b: 52.5 (#50), Mistral Small 3.1: 14.7 (#301)

Math benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
OTIS Mock AIME 2024-202588.9%3.9%
Omni-MATH68.8%24.8%
LMArena Math13891262

Knowledge gpt-oss-120b leads

gpt-oss-120b: 42.4 (#96), Mistral Small 3.1: 22.6 (#271)

Knowledge benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
GPQA Diamond75.8%41.9%
MMLU-Pro79.5%61%
GPQA (HELM)68.4%39.2%
LMArena Expert13561257
Confabulations15.7%—
Vectara Hallucination Rate14.2%—

Multimodal Not comparable

gpt-oss-120b: —, Mistral Small 3.1: 33.2 (#99)

Multimodal benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
LMArena Vision—1136

Multilingual gpt-oss-120b leads

gpt-oss-120b: 48.0 (#147), Mistral Small 3.1: 41.2 (#209)

Multilingual benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
LMArena Non-English13511255
LMArena Chinese13851253
LMArena French13691273
LMArena German13531266
LMArena Japanese13311208
LMArena Korean12821206
LMArena Russian13431263
LMArena Spanish13891283

Instruction Following gpt-oss-120b leads

gpt-oss-120b: 69.3 (#173), Mistral Small 3.1: 63.6 (#230)

Instruction Following benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
IFEval83.6%75%
LMArena Instruction Following13181264

Long Context Mistral Small 3.1 leads

gpt-oss-120b: 31.4 (#278), Mistral Small 3.1: 39.5 (#178)

Long Context benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
LMArena Longer Query13191299
Fiction.LiveBench44.4%—

Writing & Preference gpt-oss-120b leads

gpt-oss-120b: 46.5 (#217), Mistral Small 3.1: 37.0 (#259)

Writing & Preference benchmarks
Benchmarkgpt-oss-120bMistral Small 3.1
LMArena Text13651277
LMArena Creative Writing12751253
EQ-Bench Creative Writing961761
WildBench84.5%78.8%
LMArena Multi-Turn13401270
Short-Story Creative Writing77.1%—

Frequently asked questions

Is gpt-oss-120b better than Mistral Small 3.1?

gpt-oss-120b is the stronger model overall, scoring 36.3 to 31.7 on the Noometry Index.

Which is cheaper, gpt-oss-120b or Mistral Small 3.1?

gpt-oss-120b is cheaper. It lists at $0.037 per million input tokens and $0.17 per million output tokens; Mistral Small 3.1 lists at $0.35 and $0.56.

Is gpt-oss-120b or Mistral Small 3.1 better for coding?

Mistral Small 3.1 scores higher on coding benchmarks: 38.3 versus 33.5 in the Noometry coding category.

Which has the bigger context window?

gpt-oss-120b does, with 131K tokens against 128K.

How many benchmarks do gpt-oss-120b and Mistral Small 3.1 share?

27 benchmarks have published results for both models. gpt-oss-120b has 48 scored results on Noometry and Mistral Small 3.1 has 28.

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