Setting Up and Running OpenAI’s ‘gpt-oss-20b’ Open Weight Model Locally on Your Mac.

OpenAI has released its open weight model, gpt-oss-20b, which can be run locally on Macs with Apple silicon. The medium model is suitable for Macs with enough resources and can be used freely. However, it lacks modern chatbot features and requires at least 16GB RAM to run. Installation is simple, and users can download the Ollama app and follow prompts to get started. The model's performance depends on hardware resources, and Macs with more RAM will perform better.

OpenAI has recently released its open weight model, gpt-oss-20b, which can be run locally on Macs with Apple silicon. This model, designed to be a medium open weight model, offers users the opportunity to experiment with large language models on their own hardware. The gpt-oss-20b model is particularly suited for Macs with sufficient resources, providing a free and accessible tool for those interested in AI experimentation.

The gpt-oss-20b model is not without its limitations. By default, it lacks many of the modern chatbot features found in services like ChatGPT. Additionally, it requires at least 16GB of RAM to run effectively. However, for users with Macs that meet these requirements, the model can be a powerful tool for local experimentation.

The installation process for gpt-oss-20b is straightforward. Users can download the Ollama app, which serves as the interface for interacting with the model. After installing Ollama, users can pull the model using a simple command in Terminal. The model will then be downloaded and can be launched directly from the Ollama app.

The performance of gpt-oss-20b is heavily dependent on the hardware resources available. Macs with more RAM will perform better, allowing for faster processing times and more efficient use of the model. Users should be aware that running the model may significantly slow down their Mac, as it will use all available resources to process requests.

To remove the local model and reclaim disk space, users can enter a specific command in Terminal. This allows for easy management of the model's presence on the user's Mac.

In summary, OpenAI's gpt-oss-20b offers a unique opportunity for Mac users to experiment with large language models locally. While it has limitations and requires significant hardware resources, it provides a valuable tool for those interested in AI experimentation. Users should be prepared for the potential impact on their Mac's performance and ensure they have the necessary resources to run the model effectively.

[1] https://9to5mac.com/2025/08/06/how-to-run-gpt-oss-20b-on-mac/