OpenAI GPT-4.5 vs OpenAI gpt-oss-120b — side-by-side specs.
OpenAI GPT-4.5 | OpenAI gpt-oss-120b | |
|---|---|---|
| Overview | ||
| Company | OpenAI | OpenAI |
| Release date | Feb 27 2025 | Aug 5 2025 |
| Model type | — | — |
| Open source | No | Yes |
| Specifications | ||
Parameters | — | — |
Context window | — | — |
| Benchmarks | ||
| Timeline | ||
| Release gap | GPT-4.5 shipped 159 days before gpt-oss-120b | |
GPT-4.5 and gpt-oss-120b don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. GPT-4.5 shipped 159 days before gpt-oss-120b, so benchmark comparisons should account for the intervening progress.
gpt-oss-120b is an open-source / open-weight model; GPT-4.5 is proprietary.
Direct benchmark comparisons are unavailable — GPT-4.5 and gpt-oss-120b don't publish scores on any of the same benchmarks.