[stingraycharles]

Yes but then what does the grandparent mean with “unless you specify a specific model” ? Do they mean “if you select auto, it automatically decides between instant or thinking” ?

That’s… hardly something worth mentioning.

[rabf]

If you have the paid subscription you can choose what model your question is routed to. Current options in the UI are GPT-5.1 Instant, GPT-5.1 Thinking, GPT-5 Instant, GPT-5 thinking mini, GPT-5 thinking, GPT-4o, GPT-4.1, o3 and o4-mini. Options like deep-research will affect the reasoning level used. There is a lot that goes on behind the scenes in the chatgpt app with things like tool use or function calling coming into play as well. Ultimately what OpenAI will be trying/hoping to do is give you a satifactory result using the least amount of compute possible - this is where the autorouter is very useful for them and obstensibly for the user who would not know which one to pick. I mostly just use the API's these days as I like to be the one who decides who/what I am talking to.