GPT-OSS 20B

In non-nerd speak

Who makes it: OpenAI. The files come from the maker's own Hugging Face account.

License: Apache License 2.0. A standard open source license. You can use, change, and share it, even to make money. Keep the license notice.

Business use: Yes. Business use is allowed. Keep the license and notice files when you share it.

Training data: We have not found a full public data release. Not yet checked in depth.

Will it run on my computer?

Pick a computer with at least 32 GB of memory. On a Mac, that is the unified memory. On a PC, a graphics card with that much VRAM is fastest. A PC with only normal RAM will also work, just slower. This model uses a mix of experts. Only part of it works on each word, so it runs faster than its size suggests.

OpenAI says it runs in 16 GB of memory (source). Our estimate is about 17 GB. So 16 GB machines will be a tight fit. Close the 40 browser tabs first.

Not sure? Use our pick-by-computer guide.

How to run it in LM Studio

1. Get LM Studio from lmstudio.ai and open it.
2. Open the Discover tab. Search for lmstudio-community/gpt-oss-20b-GGUF.
3. Pick a file that ends in Q4_K_M. It is the best mix of size and quality for most people.
4. Click Download. When it is done, open a new chat and load the model.

The files are GGUF builds that LM Studio can load. We checked that this repo exists on Oct 14, 2026. Full LM Studio guide.

How to use it with Hermes

Does it fit? Yes. Its memory window is big enough for Hermes.

1. Load the model in LM Studio. Set the context length to at least 64000.
2. In LM Studio, open the Developer tab and start the server.
3. In a terminal, run hermes model. Choose LM Studio and press Enter to keep http://localhost:1234/v1.
4. Pick this model from the list. Then run hermes to start.

Steps based on the Hermes docs. Full Hermes guide.

Common questions

Is GPT-OSS 20B truly open source?

Yes, OSI-approved license. A standard open source license. You can use, change, and share it, even to make money. Keep the license notice.

Can I use GPT-OSS 20B for my business?

Yes. Business use is allowed. Keep the license and notice files when you share it.

Do I need to sign up to download GPT-OSS 20B?

No. Download without an account.

How much memory does GPT-OSS 20B need?

OpenAI says it runs within 16 GB of memory. Our estimate is about 17 GB of RAM for a 4-bit file of about 12.5 GB. This is a rough guide, not a test. So a 16 GB machine will be a tight fit.

Similar models to compare

Same maker first, then models that need about the same memory.

Where GPT-OSS 20B shows up

• Best local AI for Mac
• Best local AI for business use
• Other models that fit a 32 GB computer
• What its license means

Sources we checked

If the maker's page and this page disagree, trust the maker. Tell us what we got wrong.