# Devstral Small 2505 vs GPT-5.5 Pro

> GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 33.9 on the Noometry Index. Devstral Small 2505 costs 450× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/devstral-small-vs-gpt-5-5-pro
- Last updated: 2026-10-10
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. Devstral Small 2505 scores higher in 0 categories and GPT-5.5 Pro in 1 category; one gap is clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5.5 Pro leads 73.6 to 19.1.
- The biggest single-benchmark swing is CritPt: 0% for Devstral Small 2505 and 30.6% for GPT-5.5 Pro.
- Devstral Small 2505 is cheaper at $0.10 / $0.30 per million input/output tokens, against $30 / $180 for GPT-5.5 Pro.
- GPT-5.5 Pro accepts more context: 1.05M tokens versus 128K.
- Devstral Small 2505 has downloadable open weights; the other is API-only.

## Snapshot

| | Devstral Small 2505 | GPT-5.5 Pro |
|---|---|---|
| Provider | Mistral AI | OpenAI |
| Noometry Index | 33.9 | 64.3 |
| Rank | 228 | 7 |
| Context | 128K | 1.05M |
| Input $/M | $0.10 | $30 |
| Output $/M | $0.30 | $180 |
| Weights | Open | Proprietary |

## Coding

- Devstral Small 2505: 38.6 (#160)
- GPT-5.5 Pro: —

| Benchmark | Devstral Small 2505 | GPT-5.5 Pro |
|---|---|---|
| SWE-bench Verified (bash only) | 56.4% | — |
| SciCode | 28.8% | — |

## Reasoning

- Devstral Small 2505: 19.1 (#243)
- GPT-5.5 Pro: 73.6 (#7)

| Benchmark | Devstral Small 2505 | GPT-5.5 Pro |
|---|---|---|
| CritPt | 0% | 30.6% |
| ARC-AGI-2 | — | 84.6% |
| SimpleBench | — | 76.9% |
| Kagi LLM Benchmark | 37.7% | — |
| ARC-AGI-1 | — | 96.5% |
| Chess Puzzles | — | 64% |
| DTBench | — | 96% |
| LMCA | — | 53.9% |
| Epoch Capabilities Index | — | 162.45 |

## Math

- Devstral Small 2505: —
- GPT-5.5 Pro: 83.8 (#8)

| Benchmark | Devstral Small 2505 | GPT-5.5 Pro |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 87.7% |
| FrontierMath Tier 4 | — | 78% |
| OTIS Mock AIME 2024-2025 | — | 100% |
| FrontierMath (Feb 2025 set) | — | 52.4% |
| FrontierMath Tier 4 (v1) | — | 39.6% |

## Knowledge

- Devstral Small 2505: —
- GPT-5.5 Pro: 64.2 (#17)

| Benchmark | Devstral Small 2505 | GPT-5.5 Pro |
|---|---|---|
| GPQA Diamond | — | 93.9% |

## FAQ

### Is Devstral Small 2505 better than GPT-5.5 Pro?

GPT-5.5 Pro is the stronger model overall, scoring 64.3 to 33.9 on the Noometry Index. Devstral Small 2505 costs 450× less per token, which makes it the better buy when GPT-5.5 Pro's lead doesn't matter for your workload.

### Which is cheaper, Devstral Small 2505 or GPT-5.5 Pro?

Devstral Small 2505 is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; GPT-5.5 Pro lists at $30 and $180.

### Which has the bigger context window?

GPT-5.5 Pro does, with 1.05M tokens against 128K.

### How many benchmarks do Devstral Small 2505 and GPT-5.5 Pro share?

1 benchmark has published results for both models. Devstral Small 2505 has 4 scored results on Noometry and GPT-5.5 Pro has 14.