Model comparison

GPT-5 Nano vs Mistral Small 3.1

GPT-5 Nano is the stronger model overall, scoring 33.5 to 31.7 on the Noometry Index.

Last verified . 27 shared benchmarks.

GPT-5 Nano OpenAI

33.5

Rank #241 Confirmed

Mistral Small 3.1 Mistral AI

31.7

Rank #269 Confirmed

Summary

  • They share 27 benchmarks with published results for both. GPT-5 Nano scores higher in 5 categories and Mistral Small 3.1 in 4 categories; 9 gaps are clear of the uncertainty.
  • The widest gap is in math, where GPT-5 Nano leads 29.4 to 14.7.
  • The biggest single-benchmark swing is OTIS Mock AIME 2024-2025: 81.1% for GPT-5 Nano and 3.9% for Mistral Small 3.1.
  • GPT-5 Nano is cheaper at $0.05 / $0.40 per million input/output tokens, against $0.35 / $0.56 for Mistral Small 3.1.
  • GPT-5 Nano accepts more context: 400K tokens versus 128K.
  • Mistral Small 3.1 has downloadable open weights; the other is API-only.

Side by side

GPT-5 Nano and Mistral Small 3.1 specifications
GPT-5 NanoMistral Small 3.1
ProviderOpenAIMistral AI
Noometry Index33.531.7
Released2025-08-072025-03-17
WeightsProprietaryOpen
Context window400K128K
Max output128K102K
Input $ / M tokens$0.05$0.35
Output $ / M tokens$0.40$0.56
Results tracked4928

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Category by category

Coding Mistral Small 3.1 leads

GPT-5 Nano: 33.6 (#254), Mistral Small 3.1: 38.3 (#179)

Coding benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
LMArena Coding13511309
SWE-bench Verified (bash only)34.8%—
WeirdML38.1%—
ALE-Bench718.67—

Agentic & Tool Use Not comparable

GPT-5 Nano: 25.8 (#106), Mistral Small 3.1: —

Agentic & Tool Use benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
Terminal-Bench21.8%—
Berkeley Function Calling Leaderboard51.5%—

Reasoning Mistral Small 3.1 leads

GPT-5 Nano: 16.3 (#306), Mistral Small 3.1: 19.7 (#254)

Reasoning benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
Chess Puzzles27%1%
LMArena Hard Prompts13281278
Epoch Capabilities Index139.38127.48
ARC-AGI-22.6%—
Kagi LLM Benchmark62.2%—
ARC-AGI-120.7%—
Mystery Game Puzzles9%—
DTBench62.7%—
LMCA7.9%—
ForecastBench59.1—

Math GPT-5 Nano leads

GPT-5 Nano: 29.4 (#241), Mistral Small 3.1: 14.7 (#301)

Math benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
OTIS Mock AIME 2024-202581.1%3.9%
Omni-MATH54.6%24.8%
LMArena Math13171262
FrontierMath (Tiers 1-3)20%—
FrontierMath Tier 42.4%—
ProofBench12%—
MATH Level 595.2%—
FrontierMath (Feb 2025 set)8.3%—
FrontierMath Tier 4 (v1)2.1%—

Knowledge GPT-5 Nano leads

GPT-5 Nano: 35.9 (#178), Mistral Small 3.1: 22.6 (#271)

Knowledge benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
GPQA Diamond69.4%41.9%
MMLU-Pro77.8%61%
GPQA (HELM)67.9%39.2%
LMArena Expert13211257
SimpleQA Verified11.7%—
Vectara Hallucination Rate10.5%—

Multimodal Mistral Small 3.1 leads

GPT-5 Nano: 31.3 (#108), Mistral Small 3.1: 33.2 (#99)

Multimodal benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
LMArena Vision11591136
VPCT37.2%—

Multilingual GPT-5 Nano leads

GPT-5 Nano: 45.3 (#172), Mistral Small 3.1: 41.2 (#209)

Multilingual benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
LMArena Non-English13131255
LMArena Chinese13561253
LMArena German13271266
LMArena Japanese12261208
LMArena Korean12691206
LMArena Russian12961263
LMArena Spanish13601283
LMArena French—1273

Instruction Following GPT-5 Nano leads

GPT-5 Nano: 75.0 (#79), Mistral Small 3.1: 63.6 (#230)

Instruction Following benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
IFEval93.2%75%
LMArena Instruction Following13061264

Long Context Mistral Small 3.1 leads

GPT-5 Nano: 31.3 (#281), Mistral Small 3.1: 39.5 (#178)

Long Context benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
LMArena Longer Query13121299
Fiction.LiveBench44.4%—

Writing & Preference GPT-5 Nano leads

GPT-5 Nano: 39.1 (#249), Mistral Small 3.1: 37.0 (#259)

Writing & Preference benchmarks
BenchmarkGPT-5 NanoMistral Small 3.1
LMArena Text13201277
LMArena Creative Writing12491253
EQ-Bench Creative Writing705761
WildBench80.6%78.8%
LMArena Multi-Turn13111270

Frequently asked questions

Is GPT-5 Nano better than Mistral Small 3.1?

GPT-5 Nano is the stronger model overall, scoring 33.5 to 31.7 on the Noometry Index.

Which is cheaper, GPT-5 Nano or Mistral Small 3.1?

GPT-5 Nano is cheaper. It lists at $0.05 per million input tokens and $0.40 per million output tokens; Mistral Small 3.1 lists at $0.35 and $0.56.

Is GPT-5 Nano or Mistral Small 3.1 better for coding?

Mistral Small 3.1 scores higher on coding benchmarks: 38.3 versus 33.6 in the Noometry coding category.

Which has the bigger context window?

GPT-5 Nano does, with 400K tokens against 128K.

How many benchmarks do GPT-5 Nano and Mistral Small 3.1 share?

27 benchmarks have published results for both models. GPT-5 Nano has 49 scored results on Noometry and Mistral Small 3.1 has 28.

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