Model comparison
Devstral Small 2505 vs GPT-5.3 Codex
GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 33.9 on the Noometry Index. Devstral Small 2505 costs 32× less per token, which makes it the better buy when GPT-5.3 Codex's lead doesn't matter for your workload.
Last verified . 0 shared benchmarks.
Mistral AISummary
- The widest gap is in coding, where GPT-5.3 Codex leads 48.5 to 38.6.
- Devstral Small 2505 is cheaper at $0.10 / $0.30 per million input/output tokens, against $1.75 / $14 for GPT-5.3 Codex.
- GPT-5.3 Codex 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-5.3 Codex | |
|---|---|---|
| Provider | Mistral AI | OpenAI |
| Noometry Index | 33.9 | 45.5 |
| Released | 2025-05-07 | 2026-02-05 |
| Weights | Open | Proprietary |
| Context window | 128K | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $0.10 | $1.75 |
| Output $ / M tokens | $0.30 | $14 |
| Results tracked | 4 | 8 |
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Category by category
Coding GPT-5.3 Codex leads
Devstral Small 2505: 38.6 (#160), GPT-5.3 Codex: 48.5 (#51)
| Benchmark | Devstral Small 2505 | GPT-5.3 Codex |
|---|---|---|
| SWE-bench Verified | — | 74.8% |
| SWE-bench Verified (bash only) | 56.4% | — |
| LMArena WebDev | — | 1408 |
| SciCode | 28.8% | — |
| WeirdML | — | 79.3% |
| ALE-Bench | — | 1,655 |
Agentic & Tool Use Not comparable
Devstral Small 2505: —, GPT-5.3 Codex: 47.8 (#9)
| Benchmark | Devstral Small 2505 | GPT-5.3 Codex |
|---|---|---|
| Terminal-Bench | — | 78.4% |
| METR Time Horizons | — | 74.5% |
| Vending-Bench 2 | — | 5,940 |
Reasoning Not comparable
Devstral Small 2505: 19.1 (#243), GPT-5.3 Codex: —
| Benchmark | Devstral Small 2505 | GPT-5.3 Codex |
|---|---|---|
| Kagi LLM Benchmark | 37.7% | — |
| CritPt | 0% | — |
| Epoch Capabilities Index | — | 156.84 |
Frequently asked questions
Is Devstral Small 2505 better than GPT-5.3 Codex?
GPT-5.3 Codex is the stronger model overall, scoring 45.5 to 33.9 on the Noometry Index. Devstral Small 2505 costs 32× less per token, which makes it the better buy when GPT-5.3 Codex's lead doesn't matter for your workload.
Which is cheaper, Devstral Small 2505 or GPT-5.3 Codex?
Devstral Small 2505 is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; GPT-5.3 Codex lists at $1.75 and $14.
Is Devstral Small 2505 or GPT-5.3 Codex better for coding?
GPT-5.3 Codex scores higher on coding benchmarks: 48.5 versus 38.6 in the Noometry coding category.
Which has the bigger context window?
GPT-5.3 Codex does, with 400K tokens against 128K.
How many benchmarks do Devstral Small 2505 and GPT-5.3 Codex share?
0 benchmarks have published results for both models. Devstral Small 2505 has 4 scored results on Noometry and GPT-5.3 Codex has 8.