OpenAI GPT-5.1 vs OpenAI gpt-oss-120b — side-by-side specs.
OpenAI GPT-5.1 | OpenAI gpt-oss-120b | |
|---|---|---|
| Overview | ||
| Company | OpenAI | OpenAI |
| Release date | Nov 12 2025 | Aug 5 2025 |
| Model type | — | — |
| Open source | No | Yes |
| Specifications | ||
Parameters | — | — |
Context window | — | — |
| Benchmarks | ||
Coding SWE-Bench VerifiedReal coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better. | 76.3% | — |
Science GPQA DiamondGraduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. | 88.1% | — |
Multimodal MMMUTests the AI on understanding images and text together across many college subjects. Higher is better. | 76% | — |
| Timeline | ||
| Release gap | gpt-oss-120b shipped 99 days before GPT-5.1 | |
GPT-5.1 and gpt-oss-120b don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. gpt-oss-120b shipped 99 days before GPT-5.1, so benchmark comparisons should account for the intervening progress.
gpt-oss-120b is an open-source / open-weight model; GPT-5.1 is proprietary.
Direct benchmark comparisons are unavailable — GPT-5.1 and gpt-oss-120b don't publish scores on any of the same benchmarks.