gpt-oss-20b
gpt-oss-20b is an open-weight language model from OpenAI, released on August 5, 2025.
- Developer
- OpenAI
- Released
- August 5, 2025
- Total parameters
- 21B
- Active parameters per token
- 3.6B
- Architecture
- MoE
- Context window
- 128K
- Input
- Text
- License
- Apache 2.0
- Commercial use
- Yes
- Official weights, GB
- 13.8 GB
- Hugging Face repository
- huggingface.co
- Checked on
gpt-oss-20b is a mixture-of-experts model with 21B total parameters, of which 3.6B are active for each token. OpenAI lists a context window of 128K tokens. The model takes text input. The weights are released under Apache 2.0, which allows commercial use.
The official weights on Hugging Face take about 13.8 GB. Running the model needs at least that much memory across GPUs and system RAM, plus room for the context cache; quantized versions need less.
- Total parameters, billions
- 21B
- Active parameters, billions
- 3.6B
- Context window, tokens
- 128K
- License type
- Apache 2.0
- License conditions
- Apache 2.0, with a short usage policy in the repository. No user or revenue limits.
- Weights precision
- MXFP4 + BF16
- License text
- huggingface.co
- Sources
Page URL Hugging Face model card https://huggingface.co/openai/gpt-oss-20b/raw/main/README.md Hugging Face weights index https://huggingface.co/openai/gpt-oss-20b/raw/main/model.safetensors.index.json openai.com https://openai.com/index/introducing-gpt-oss/ Hugging Face API https://huggingface.co/api/models/openai/gpt-oss-20b?expand=safetensors
Questions
What license does gpt-oss-20b use?
How much memory does gpt-oss-20b need?
How many parameters does gpt-oss-20b have?
How does gpt-oss-20b compare with gpt-oss-120b?
Sources
Every figure comes from the developer’s model card, license text and official announcements, and from the model’s Hugging Face repository metadata. Each model page lists its sources and the date they were checked; the register is rechecked every week.