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gpt-oss-20b
gpt-oss-20b is an open-weight model from OpenAI, released Aug 5, 2025. It ranks #262 of 351 on the LMArena text leaderboard with a rating of 1288. It costs $0.018 per million input tokens and $0.09 per million output tokens, with a 128K-token context window.
- Developer
- OpenAI
- Released
- Aug 5, 2025
- Context window
- 128K
- Price in / out, per 1M tokens
- $0.018 / $0.09
- Weights
- Open · Apache 2.0
- Inputs
- Text
- Reasoning
- Yes
- Tool use
- Yes
- Hugging Face downloads, 30 days
- 5.8M
- Hugging Face likes
- 5.2K
The rating LMArena published at each update since Aug 7, 2025. Ratings move as votes come in and new models join.
Benchmarks
| Benchmark | Score bar | Accuracy | Rank | Cost / test |
|---|---|---|---|---|
| LiveCodeBenchCoding | 80.39% | 70 / 143 | $0.07 / $0.3 | |
| MedQAMedicine | 82.88% | 63 / 92 | $0.07 / $0.3 | |
| GPQA DiamondReasoning | 68.94% | 99 / 138 | $0.07 / $0.3 | |
| MMLU-ProReasoning | 71.64% | 118 / 138 | $0.07 / $0.3 | |
| AIMEReasoning | 86.04% | 34 / 96 | $0.07 / $0.3 |
Vals AI, as of Oct 24, 2026.
LMArena, by category
| Leaderboard | Rating | Rank | Votes |
|---|---|---|---|
| TextLMArena | 1288 | 262 / 351 | 10.4K |
| CodingLMArena | 1307 | 256 / 346 | 2.1K |
| MathLMArena | 1317 | 228 / 339 | 678 |
| Creative writingLMArena | 1201 | 307 / 349 | 1.2K |
| Instruction followingLMArena | 1236 | 291 / 351 | 2.5K |
| Hard promptsLMArena | 1274 | 264 / 351 | 4.7K |
| Multi-turnLMArena | 1268 | 279 / 349 | 1.8K |
| Long queriesLMArena | 1250 | 291 / 330 | 2.1K |
| ExpertLMArena | 1258 | 250 / 305 | 506 |
| Legal and governmentIndustries | 1280 | 272 / 325 | 678 |
| Medicine and healthcareIndustries | 1310 | 237 / 325 | 564 |
| Business and financeIndustries | 1283 | 250 / 344 | 1.8K |
| ChineseLanguages | 1315 | 241 / 328 | 665 |
| SpanishLanguages | 1268 | 236 / 249 | 284 |
| GermanLanguages | 1255 | 227 / 261 | 217 |
| JapaneseLanguages | 1244 | 189 / 236 | 246 |
LMArena, CC BY 4.0, as of Oct 22, 2026. Where a model is rated at several effort levels, its best is shown.
Compare gpt-oss-20b
OpenAI
The lab behind GPT and ChatGPT, which brought large language models to hundreds of millions of people. Founded 2015, based in San Francisco. openai.com
Questions
Who makes gpt-oss-20b?
gpt-oss-20b is made by OpenAI, founded 2015 and based in San Francisco.
How much does gpt-oss-20b cost?
$0.018 per million input tokens and $0.09 per million output tokens, at its provider’s list price.
What is gpt-oss-20b’s context window?
128K tokens (131,072).
How does gpt-oss-20b rank?
#262 of 351 on LMArena’s text leaderboard, rated 1288 (95% interval 1281–1294) from 10,417 votes, as of Oct 22, 2026.
Is gpt-oss-20b open source?
gpt-oss-20b has open weights under the Apache 2.0 license, downloadable from Hugging Face (openai/gpt-oss-20b).