OpenAI - Mixture of experts - verified
Run gpt-oss-20b locally
gpt-oss-20b is a 20.9B mixture-of-experts (3.6B active) model from OpenAI with a 131K-token context window, released under Apache 2.0 (commercial use is allowed); the smallest listed download is 11.2 GB, the MXFP4-Q4 MLX build from mlx-community/gpt-oss-20b-MXFP4-Q4.
Official weights: openai/gpt-oss-20b
- Total params
- 20.9B
- Active params
- 3.6B
- Context
- 131K
- Smallest download
- 11.2 GB
Fits in
Smallest download at most 85% of memoryDownloads
The official weights and every quantization listed for this model, with file sizes from Hugging Face.
| Download | Format | Size | Repo |
|---|---|---|---|
Official weights | MXFP4 | 13.8 GB | openai/gpt-oss-20b |
MXFP4 | GGUF | 12.1 GB | ggml-org/gpt-oss-20b-GGUF |
Q4_K_M | GGUF | 11.6 GB | unsloth/gpt-oss-20b-GGUF |
Q8_0 | GGUF | 12.1 GB | unsloth/gpt-oss-20b-GGUF |
MXFP4-Q4Smallest listed | MLX | 11.2 GB | mlx-community/gpt-oss-20b-MXFP4-Q4 |
GB is decimal: 1 GB = 10^9 bytes. Add memory for the context and the operating system on top of the file size.
Run it
Copied verbatim from the page linked under each command. Server commands from model cards often assume a multi-GPU node; check the flags before you run them.
Transformers
pip install -U transformers kernels torchNot sure which runtime to use? Compare local LLM runtimes by platform, API and features.
License
- License
- Apache 2.0
apache-2.0 - Commercial use
- Commercial use: YesCommercial use is allowed.
- Gated download
- No. The files download directly.
Worth knowing
Must be prompted in OpenAI's harmony response format, and its MXFP4 MoE weights let it run within 16GB of memory.
Released (per the announcement).
FAQ
How big is the gpt-oss-20b download?
The official MXFP4 weights in openai/gpt-oss-20b are 13.8 GB. The smallest listed download is 11.2 GB, the MXFP4-Q4 MLX build from mlx-community/gpt-oss-20b-MXFP4-Q4. Plan for more memory than the file size: the context (KV cache) and the operating system need room too.
Can I use gpt-oss-20b commercially?
gpt-oss-20b is released under Apache 2.0, and commercial use is allowed. The license text is at https://huggingface.co/openai/gpt-oss-20b/blob/main/LICENSE.
How much memory do I need for gpt-oss-20b?
By this directory's rule of thumb it fits in 16 GB and up: the smallest listed download, 11.2 GB, is at most 85% of 16 GB, which leaves room for the context and the operating system.
How do I run gpt-oss-20b with Ollama?
Run "ollama run gpt-oss:20b", as shown at https://huggingface.co/openai/gpt-oss-20b. The Ollama library lists the gpt-oss:20b tag at 14GB.
What is the context length of gpt-oss-20b?
131,072 tokens. A longer context needs more memory for the KV cache, so you can run with a shorter one when memory is tight.
Sources
Last verified from the pages below.
- HF API - huggingface.co
- HF file tree - huggingface.co
- Model card - huggingface.co
- config.json - huggingface.co
- Ollama gpt-oss - ollama.com
- OpenAI: Introducing gpt-oss - openai.com
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