Model comparison
Devstral Small 2505 vs GPT-5 Nano
Devstral Small 2505 and GPT-5 Nano score almost the same on the Noometry Index (34.3 vs 33.5), so choose on price, context window or the category you care about most.
Last verified . 2 shared benchmarks.
Mistral AISummary
- They share 2 benchmarks with published results for both. Devstral Small 2505 scores higher in 2 categories and GPT-5 Nano in 0 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in coding, where Devstral Small 2505 leads 38.9 to 33.6.
- The biggest single-benchmark swing is Kagi LLM Benchmark: 37.7% for Devstral Small 2505 and 62.2% for GPT-5 Nano.
- GPT-5 Nano is cheaper at $0.05 / $0.40 per million input/output tokens, against $0.10 / $0.30 for Devstral Small 2505.
- GPT-5 Nano accepts more context: 400K tokens versus 128K.
- Devstral Small 2505 has downloadable open weights; the other is API-only.
Side by side
| Devstral Small 2505 | GPT-5 Nano | |
|---|---|---|
| Provider | Mistral AI | OpenAI |
| Noometry Index | 34.3 | 33.5 |
| Released | 2025-05-07 | 2025-08-07 |
| Weights | Open | Proprietary |
| Context window | 128K | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $0.10 | $0.05 |
| Output $ / M tokens | $0.30 | $0.40 |
| Results tracked | 4 | 49 |
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Category by category
Coding Devstral Small 2505 leads
Devstral Small 2505: 38.9 (#166), GPT-5 Nano: 33.6 (#254)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| SWE-bench Verified (bash only) | 56.4% | 34.8% |
| SciCode | 28.8% | — |
| WeirdML | — | 38.1% |
| LMArena Coding | — | 1351 |
| ALE-Bench | — | 718.67 |
Agentic & Tool Use Not comparable
Devstral Small 2505: —, GPT-5 Nano: 25.8 (#106)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| Terminal-Bench | — | 21.8% |
| Berkeley Function Calling Leaderboard | — | 51.5% |
Reasoning Devstral Small 2505 leads
Devstral Small 2505: 19.7 (#252), GPT-5 Nano: 16.3 (#306)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| Kagi LLM Benchmark | 37.7% | 62.2% |
| ARC-AGI-2 | — | 2.6% |
| ARC-AGI-1 | — | 20.7% |
| CritPt | 0% | — |
| Chess Puzzles | — | 27% |
| LMArena Hard Prompts | — | 1328 |
| Mystery Game Puzzles | — | 9% |
| DTBench | — | 62.7% |
| LMCA | — | 7.9% |
| Epoch Capabilities Index | — | 139.38 |
| ForecastBench | — | 59.1 |
Math Not comparable
Devstral Small 2505: —, GPT-5 Nano: 29.4 (#241)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 20% |
| FrontierMath Tier 4 | — | 2.4% |
| OTIS Mock AIME 2024-2025 | — | 81.1% |
| ProofBench | — | 12% |
| Omni-MATH | — | 54.6% |
| LMArena Math | — | 1317 |
| MATH Level 5 | — | 95.2% |
| FrontierMath (Feb 2025 set) | — | 8.3% |
| FrontierMath Tier 4 (v1) | — | 2.1% |
Knowledge Not comparable
Devstral Small 2505: —, GPT-5 Nano: 35.9 (#178)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| GPQA Diamond | — | 69.4% |
| SimpleQA Verified | — | 11.7% |
| MMLU-Pro | — | 77.8% |
| Vectara Hallucination Rate | — | 10.5% |
| GPQA (HELM) | — | 67.9% |
| LMArena Expert | — | 1321 |
Multimodal Not comparable
Devstral Small 2505: —, GPT-5 Nano: 31.3 (#108)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| LMArena Vision | — | 1159 |
| VPCT | — | 37.2% |
Multilingual Not comparable
Devstral Small 2505: —, GPT-5 Nano: 45.3 (#172)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| LMArena Non-English | — | 1313 |
| LMArena Chinese | — | 1356 |
| LMArena German | — | 1327 |
| LMArena Japanese | — | 1226 |
| LMArena Korean | — | 1269 |
| LMArena Russian | — | 1296 |
| LMArena Spanish | — | 1360 |
Instruction Following Not comparable
Devstral Small 2505: —, GPT-5 Nano: 75.0 (#79)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| IFEval | — | 93.2% |
| LMArena Instruction Following | — | 1306 |
Long Context Not comparable
Devstral Small 2505: —, GPT-5 Nano: 31.3 (#281)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| Fiction.LiveBench | — | 44.4% |
| LMArena Longer Query | — | 1312 |
Writing & Preference Not comparable
Devstral Small 2505: —, GPT-5 Nano: 39.1 (#249)
| Benchmark | Devstral Small 2505 | GPT-5 Nano |
|---|---|---|
| LMArena Text | — | 1320 |
| LMArena Creative Writing | — | 1249 |
| EQ-Bench Creative Writing | — | 705 |
| WildBench | — | 80.6% |
| LMArena Multi-Turn | — | 1311 |
Frequently asked questions
Is Devstral Small 2505 better than GPT-5 Nano?
Devstral Small 2505 and GPT-5 Nano score almost the same on the Noometry Index (34.3 vs 33.5), so choose on price, context window or the category you care about most.
Which is cheaper, Devstral Small 2505 or GPT-5 Nano?
GPT-5 Nano is cheaper. It lists at $0.05 per million input tokens and $0.40 per million output tokens; Devstral Small 2505 lists at $0.10 and $0.30.
Is Devstral Small 2505 or GPT-5 Nano better for coding?
Devstral Small 2505 scores higher on coding benchmarks: 38.9 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 Devstral Small 2505 and GPT-5 Nano share?
2 benchmarks have published results for both models. Devstral Small 2505 has 4 scored results on Noometry and GPT-5 Nano has 49.