GPT-5.1: A smarter, more conversational ChatGPT

Today we’re upgrading the GPT‑5 series with the release of:

• GPT‑5.1 Instant: our most-used model, now warmer, more intelligent, and better at following your instructions.

• GPT‑5.1 Thinking: our advanced reasoning model, now easier to understand and faster on simple tasks, more persistent on complex ones.

We heard clearly from users that great AI should not only be smart, but also enjoyable to talk to. GPT‑5.1 improves meaningfully on both intelligence and communication style.

We’re also making it easier for you to shape ChatGPT’s tone. Preferences on chat style vary—from person to person and even from conversation to conversation—so we’re introducing more intuitive and effective controls so ChatGPT can better match the tone you want in responses.

GPT‑5.1 Instant

GPT‑5.1 Instant, ChatGPT’s most used model, is now warmer by default and more conversational. Based on early testing, it often surprises people with its playfulness while remaining clear and useful.

We’ve also improved instruction following, so the model more reliably answers the question you actually asked.

For the first time, GPT‑5.1 Instant can use adaptive reasoning to decide when to think before responding to more challenging questions, resulting in more thorough and accurate answers, while still responding quickly. This is reflected in significant improvements on math and coding evaluations like AIME 2025 and Codeforces.

GPT‑5.1 Thinking

We’re also upgrading GPT‑5 Thinking to make it more efficient and easier to understand in everyday use. It now adapts its thinking time more precisely to the question—spending more time on complex problems while responding more quickly to simpler ones. In practice, that means more thorough answers for difficult requests and less waiting for simpler ones.

GPT‑5.1 Thinking’s default tone is also warmer and more empathetic.