OpenAI has released GPT-5.1 under the radar, which will gradually replace GPT-5 over the next few weeks and become the new default.
Some ChatGPT users already have access to the new model. As usual, the rollout began with Pro and Plus subscribers. In the meantime, you can chat with ChatGPT on Overchat AI.
Here's everything you should know about the new model.
GPT-5.1 is an upgrade to the GPT-5 series that makes the model more conversational and friendly.
OpenAI released two versions:
According to OpenAI, GPT-5.1 now responds with a warmer tone, sounding friendlier and more conversational than GPT 5.1. See the image below to compare the two models:
Which style do you prefer?
Additionally, OpenAI has made significant improvements to instruction following. The model is now better at remembering your instructions and is less likely to become confused:
Finally, adaptive reasoning is introduced: GPT-5.1 Instant can now decide when to pause and think before responding to trickier questions. This means faster answers for simple tasks and more thorough responses for complex ones.
GPT-5.1 Instant is the default model most ChatGPT users will see. It's faster, warmer, and better at following instructions.
The main difference shows up in how it handles requests. The model now handles coding and math problems more reliably than before. GPT-5.1 Instant also handles emotional or personal questions differently.
One example from OpenAI's announcement: "I spilled coffee before my meeting, do people think I'm an idiot?"
GPT-5.1 Thinking is a reasoning-focused model designed for complex problems. Although it is slower than Instant, it is better at logic, planning, and multi-step tasks.
GPT-5 had an issue where the model would spend too much time thinking about easy questions, which consumed time and tokens. It would engage in reasoning for simple questions that didn't require it.
GPT-5.1 is better at knowing when to engage reasoning and when not to. You essentially get the best of both worlds: the instant response time of easy-question models and the accuracy of reasoning models for complicated questions.
OpenAI's data makes the difference clear. GPT-5.1 is twice as fast as GPT-5 when it comes to simple tasks, but it's twice as slow when it comes to complex problems. This is beneficial because it ensures more accurate results and allows for more time to solve difficult questions.
GPT-5.1 Thinking is best used for:
You can chat with GPT-5.1 on Overchat AI as long as you have a free account. Start a new chat here.
Meanwhile, GPT-5.1 is rolling out gradually to ChatGPT users starting with paid subscribers.
If you have ChatGPT Plus or Pro, you should see it in your model picker soon. The rollout is happening over several days to keep performance stable.
Free users will get access after the paid rollout completes. In the meantime, the older GPT-5 models aren't disappearing immediately. OpenAI is keeping GPT-5 Instant and GPT-5 Thinking available for three months in the legacy models dropdown for paid subscribers.
This gives you time to compare the models and adjust to the changes. After three months, GPT-5.1 becomes the only default option.
GPT-5.1 is an improvement on the existing model, rather than a revolutionary leap. This means it won’t blow you away. However, the improvements will be noticeable in daily use.
For example, the model follows instructions more accurately. It sounds more natural in conversation. It allocates thinking time more effectively. These are all extremely tangible improvements. If you were happy with GPT-5, you will like GPT-5.1 even more.
To be balanced, this model is rather warm and friendly, so if you prefer a more concise and factual response, you may want to try Kimi K2.
On Overchat AI, you can also experiment with many more different models:
See the full list of our tools.
The best way to see what's different is to try it yourself. Here are seven prompts that highlight the improvements.
Prompt: "Reply only in six-word sentences for this entire conversation."
This tests whether the model actually sticks to your constraints. GPT-5 would break the rule, but GPT-5.1 should follow it consistently.
Prompt: "Plan a three-day Paris itinerary that includes art museums, cozy coffee shops, and minimal walking. Budget is $150 per day."
Prompt: "Review this code for bugs and suggest improvements. Keep comments concise." [Paste your code]
Prompt: "Explain quantum entanglement like I'm 10 years old."
Prompt: "I just bombed a job interview and feel like a complete failure. What should I do?"
This tests the warmer, more empathetic tone. GPT-5.1 should feel less corporate and more human in its response.
Prompt: "Give me a healthy weeknight dinner recipe under 20 minutes that a picky toddler might actually eat."
The model should deliver practical, specific advice without overthinking it.
GPT-5.1 is an upgrade, but GPT-6 promises to be a revolutionary new model. This is when we are likely to see all the significant improvements that OpenAI has been working on.
However, we might have to wait until we can test it in the real world, as OpenAI has officially confirmed that GPT-6 won't arrive in 2025. But that hasn't stopped CEO Sam Altman from teasing what's coming.
The next model will focus heavily on memory, allowing it to remember user preferences, routines, and quirks over time. Altman stated that he sees memory as the key to making ChatGPT truly personal.
Right now, every conversation with GPT starts fresh, but the memory feature would allow GPT-6 to learn personal preferences, like whether users want concise answers or detailed explanations.
This could potentially transform your AI companion from an occasional tool into something more like a personal assistant or real secretary.
Excitingly, Altman made it clear that GPT-6 will arrive sooner than the timeframe between GPT-4 and GPT-5. GPT-4 was launched in March 2023. GPT-5 was released in August 2025. That's a gap of over two years. Most analysts expect GPT-6 to arrive sometime in the first half of 2026.
For now, GPT-5.1 is the latest available version. But the groundwork for what comes next is already being laid.
OpenAI has quietly released a new model. GPT-5.1 is the latest addition to the GPT 5 family and will gradually become the new default. The new model is characterized by better instruction following, a warmer and more conversational tone, and better adaptability. It knows when to engage reasoning and when to reply instantly. It not only uses fewer resources, but also streamlines conversations.
Over the coming days, the model will be rolled out to ChatGPT users to ensure stable performance. In the meantime, you can test the new model on Overchat AI for free. Start a chat with GPT-5-1.
