OpenAI recently released an upgrade to its GPT-5 series ChatGPT with the release of GPT-5.1. The release is twofold with GPT-5.1 Instant and GPT-5.1 Thinking:
- 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.
User input indicated that ChatGPT should be conversational and easy to talk to much like human conversation unfolds and warmer by default. GPT‑5.1 Instant addresses this:
Based on early testing, it often surprises people with its playfulness while remaining clear and useful.
GPT‑5.1 Instant uses adaptive reasoning to think before responding to more complicated questions resulting in more accurate though quick answers. Math and coding evaluations like AIME 2025 and Codeforces have been have been improved greatly.
GPT‑5.1 Thinking focuses on the question asked and determines if is a simple question vs. a complex one and answers accordingly and takes more time answering complex problems is quicker to answer simpler ones:
GPT‑5.1 Thinking varies its thinking time more dynamically than GPT‑5 Thinking. On a representative distribution of ChatGPT tasks, GPT‑5.1 Thinking is roughly twice as fast on the fastest tasks and twice as slow on the slowest tasks. Thinking time was set to Standard for both models.
GPT‑5.1 Thinking answers intricate questions with clarity, understanding, and with a tone that is also warmer and more empathetic.
ChatGPT customization has been a top priority to users. With this the tone of how ChatGPT responds has expanded. Along with the default Friendly (formerly Listener), and Efficient (formerly Robot) Professional, Candid, and Quirky have been added to the lineup.
Cynical (formerly Cynic) and Nerdy (formerly Nerd) options, introduced early this year will still be available under the same dropdown in personalization settings.
How ChatGPT responds through personalization settings and question nuances is further enhanced:
We’re also experimenting with the ability to tune ChatGPT’s characteristics directly from personalization settings—including how concise, warm, or scannable its responses are, and how frequently it uses emojis. ChatGPT can also proactively offer to update these preferences during conversations when it notices you asking for a certain tone or style, without requiring you to navigate into settings.
