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, 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.
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 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’s responses are also clearer, with less jargon and fewer undefined terms. This makes our most capable model more approachable and easily understandable, especially for complex tasks at work and explaining technical concepts.
GPT‑5.1 Thinking’s default tone is also warmer and more empathetic.
This release is a step forward in both capability and usability across the models. GPT‑5.1 Auto will continue to route each query to the model best suited for it, so in most cases, you won’t need to choose a model at all. What you will notice is that answers across GPT‑5.1 feel both smarter and more natural in tone.
GPT‑5.1 Instant and Thinking begin rolling out today, starting with paid (Pro, Plus, Go, Business) users and then to free and logged-out users. Enterprise and Edu plans get a seven-day early-access toggle (off by default). After that window, GPT‑5.1 will become the sole default model.
If you check ChatGPT today, you may not see GPT‑5.1 available immediately. We plan to roll it out gradually over the next few days to help keep performance stable for everyone. We will also update GPT‑5 Pro to GPT‑5.1 Pro soon.
We’re bringing both GPT‑5.1 Instant and GPT‑5.1 Thinking to the API later this week. GPT‑5.1 Instant will be added as gpt-5.1-chat-latest, and GPT‑5.1 Thinking will be released as GPT‑5.1 in the API, both with adaptive reasoning.
GPT‑5 (Instant and Thinking) will remain available in ChatGPT under the legacy models dropdown for paid subscribers for three months, so people have time to compare and adapt at their own pace. The GPT‑5 sunset period does not affect the availability of other legacy models. Going forward, when we introduce new ChatGPT models, our approach is to give people ample space to evaluate what’s changed and share feedback, allowing us to continue innovating our frontier models while transitioning smoothly. Sunset periods will be communicated clearly and with plenty of advance notice.
GPT‑5.1 is more capable and useful, and we encourage you to try it and see the difference. Our system card addendum includes more information on our safety approach for GPT‑5.1.
And a note on naming: this update is called GPT‑5.1 to reflect meaningful improvements, while remaining within the GPT‑5 generation. Future iterative upgrades to GPT‑5 will follow the same pattern.
Alongside these model improvements, we’re making it easier to customize ChatGPT’s tone and style. People have strong and varied preferences in how ChatGPT should respond, and tailoring its tone to what sounds right for you should feel effortless.
Earlier this year, we added preset options to tailor the tone of how ChatGPT responds. Today, we’re refining those options to better reflect the most common ways people use ChatGPT. Default, Friendly (formerly Listener), and Efficient (formerly Robot) remain (with updates), and we’re adding Professional, Candid, and Quirky. These options are designed to align with what we’ve learned about how people naturally steer the model, making it quick and intuitive to choose a personality that feels uniquely right.
These personality settings apply across all models. The original Cynical (formerly Cynic) and Nerdy (formerly Nerd) options we introduced earlier this year will remain available unchanged under the same dropdown in personalization settings.
Beyond these presets, for users who want more granular control over how ChatGPT responds, 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. You can adjust or remove any of these preferences at any time.
The updated styles and tone options are rolling out today, and the ability to finetune specific characteristics is starting to roll out gradually later this week as an experiment, starting with a limited number of users. Both will continue to improve over time. Additionally, the updated GPT‑5.1 models are also better at adhering to custom instructions, giving you even more precise control over tone and behavior.
Updates you make in personalization settings now take effect across all chats right away, including ongoing conversations, so your experience stays consistent. Before, changes to base style and tone or custom instructions only applied to conversations started afterward.
Today’s GPT‑5.1 updates and new customization options are a step toward a ChatGPT that feels like it fits you—smarter, more enjoyable to talk to, and more adaptable to your preferences. Going forward, we’ll continue improving along these dimensions—there’s much more to come.
