Simon Willison’s Weblog

[on the cheaper o3] Not quantized. Weights are the same.

If we did change the model, we'd release it as a new model with a new name in the API (e.g., o3-turbo-2025-06-10). It would be very annoying to API customers if we ever silently changed models, so we never do this [1].

[1] chatgpt-4o-latest being an explicit exception

— Ted Sanders, Research Manager, OpenAI