# gpt-oss-20b

gpt-oss-20b is an AI model released by OpenAI on Aug 5 2025. It has 21B parameters, a 128k context window and open weight. At release it scored 71.5% on GPQA Diamond, 60.7% on SWE-Bench Verified and 17.3% on Humanity's Last Exam (with tools).

## Facts

| Field | Value |
| --- | --- |
| Model | gpt-oss-20b |
| Developer | OpenAI |
| Release date | Tuesday, Aug 5 2025 |
| Licensing | Open Weight |
| Parameters | 21B |
| Context window | 128k |

## Benchmark scores published at release

| Benchmark | Score | Source | What it measures |
| --- | --- | --- | --- |
| SWE-Bench Verified | 60.7% | Lab | Real 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. |
| Humanity's Last Exam (no tools) | 10.9% | Lab | Humanity's Last Exam — extremely hard expert questions across many subjects, written so you can't just look up the answer. “No tools” means the AI answers on its own. Higher is better. |
| Humanity's Last Exam (with tools) | 17.3% | Lab | Humanity's Last Exam — extremely hard expert questions across many subjects. “With tools” means the AI is allowed to search the web or run code while answering. Higher is better. |
| GPQA Diamond | 71.5% | Lab | Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. |
| MMLU | 85.3% | Lab | A 57-subject multiple-choice exam — history, law, medicine, maths — that was the standard measure of how much a model knows from 2020 until roughly 2024, when frontier scores crowded into the high 80s and labs moved on to harder tests. The scores here were published years apart under different testing setups, so read them as a historical record rather than a like-for-like ranking. Higher is better. |

## Questions and answers

### When was gpt-oss-20b released?

gpt-oss-20b was released by OpenAI on Tuesday, Aug 5 2025.

### Who made gpt-oss-20b?

gpt-oss-20b was built by OpenAI. Creators of ChatGPT and the GPT series of models. Pioneered large-scale language model research.

### What benchmark scores did gpt-oss-20b get?

gpt-oss-20b reports 5 tracked benchmark scores — SWE-Bench Verified: 60.7%; Humanity's Last Exam (no tools): 10.9%; Humanity's Last Exam (with tools): 17.3%; GPQA Diamond: 71.5%; MMLU: 85.3%. Scores are the figures published at release by OpenAI.

### What is the context window of gpt-oss-20b?

gpt-oss-20b has a context window of 128k. That is the maximum amount of input plus output the model can hold in a single request.

### How many parameters does gpt-oss-20b have?

gpt-oss-20b is reported at 21B parameters.

### Is gpt-oss-20b open source?

Partly. gpt-oss-20b is an open-weight model: the trained weights are free to download and run locally or on your own infrastructure, but the training data and code are not fully released and the license may restrict some commercial uses. It is not open source in the strict sense.

### What came before and after gpt-oss-20b?

OpenAI's previous tracked release was gpt-oss-120b on Aug 5 2025. It was followed by GPT-5 on Aug 7 2025.


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Canonical page: https://aireleasetracker.com/model/openai/gpt-oss-20b
Full dataset: https://aireleasetracker.com/llms-full.txt · JSON: https://aireleasetracker.com/models.json
Source: AI Release Tracker (https://aireleasetracker.com). Benchmark scores are the figures published by the releasing lab at launch.