OpenAI just released GPT-5.1, a major update that makes ChatGPT smarter and more natural to use. This isn't a complete overhaul like GPT-5 was. Instead, it fixes problems users found in GPT-5 and adds new features that make AI conversations feel more human.

The update brings two specialized models: GPT-5.1 Instant for quick tasks and GPT-5.1 Thinking for complex problems. Both models use adaptive reasoning, which means they adjust how much "thinking time" they spend based on your question. Simple questions get fast answers. Hard questions get more processing power.

GPT-5.1 Instant is warmer by default and more conversational, while GPT-5.1 Thinking has clearer responses with less jargon and fewer undefined terms. You can also customize how ChatGPT talks to you with new personality controls. These improvements make GPT-5.1 feel less robotic and more like talking to a helpful friend.

For developers, GPT-5.1 brings faster coding performance, extended prompt caching, and new tools that make building AI applications easier. The model runs 2-3 times faster on everyday tasks while maintaining top-tier intelligence.

What Makes GPT-5.1 Different

GPT-5.1 splits into two coordinated models that work together. Think of it like having two assistants: one who's quick on their feet, and another who takes time to think deeply about hard questions.

GPT-5.1 Instant handles your everyday ChatGPT needs. It answers questions fast, helps with writing, summarizes articles, and handles general conversation. Based on early testing, it often surprises people with its playfulness while remaining clear and useful. This model feels more natural and less like you're talking to a computer.

GPT-5.1 Thinking tackles complex problems that need deeper reasoning. It's better at math, logic, multi-step planning, and technical explanations. When you ask a difficult question, this model spends more time working through the answer to give you better results.

Both models use automatic routing. You don't have to pick which one to use. ChatGPT automatically chooses the best model for your question. If you want control, you can manually select Instant or Thinking mode for specific tasks.

Adaptive Reasoning: Smarter Resource Allocation

Adaptive reasoning is the biggest technical upgrade in GPT-5.1. The model dynamically decides how much computational power to use based on your question's difficulty.

When asked "show an npm command to list globally installed packages", GPT-5.1 answers in 2 seconds instead of 10 seconds. That's because the model recognizes this as a simple query and doesn't waste time overthinking it.

For complex questions, GPT-5.1 allocates more processing time. This makes results more accurate and context-aware. You get fast answers for easy questions and thorough answers for hard ones.

This approach saves both time and money. Balyasny Asset Management said GPT-5.1 "consistently used about half as many tokens as leading competitors at similar or better quality" across their tool-heavy reasoning tasks. Fewer tokens mean lower API costs for developers and faster performance for everyone.

Warmer, More Conversational Tone

One of the most noticeable changes is how GPT-5.1 sounds. The model now defaults to a warmer, friendlier tone that feels more human.

This wasn't a minor tweak. OpenAI redesigned the base personality of both models to be more conversational. Users complained that GPT-5 felt too formal and robotic. GPT-5.1 addresses this directly.

The warmer tone works across all interactions. Whether you're asking for help with homework, brainstorming ideas, or getting technical explanations, the model sounds more natural and engaging.

This doesn't mean the model is less professional. It just means conversations feel more like talking to a knowledgeable friend instead of reading from a textbook.

Revolutionary Personality Controls

GPT-5.1 gives you unprecedented control over how ChatGPT responds. You can adjust the AI's personality to match your preferences.

To customize your experience, click "Customize ChatGPT" in the top right menu. You'll find several preset personality options:

• Default: Balanced and versatile for general use
• Friendly: Warm and supportive, like talking to a helpful companion
• Professional: Formal and structured for business settings
• Efficient: Direct and concise, no extra words
• Candid: Straightforward and honest without sugar-coating
• Quirky: Playful and creative with personality

You can also fine-tune specific characteristics using experimental sliders. Control how concise responses are, how warm the tone feels, how scannable the formatting is, and even how often the model uses emojis.

These controls apply across both Instant and Thinking modes. Your personality settings stick, so you don't have to adjust them for every conversation.

The updated GPT-5.1 models also adhere more closely to custom instructions, giving you more precise tone and behavior control. If you've set custom instructions, GPT-5.1 follows them better than previous versions.

Better Instruction Following

GPT-5.1 is significantly better at following your instructions. This was a major complaint about GPT-5, and OpenAI made it a priority to fix.

When you ask the model to do something specific, it's more likely to actually do it. Want a response in bullet points? You'll get bullet points. Need a formal tone for a business email? The model will match that tone consistently.

This improvement matters most for complex requests with multiple requirements. If you ask for a 500-word article in a specific format with certain examples, GPT-5.1 is more likely to hit all those requirements without you having to repeat yourself.

Better instruction following means less back-and-forth. You spend less time correcting the model and more time getting useful results.

Faster Performance on Simple Tasks

On a representative distribution of ChatGPT tasks, GPT-5.1 is much faster at the easier tasks, even at high reasoning effort. The model recognizes when a question is straightforward and responds quickly.

This speed improvement is noticeable in everyday use. Asking for definitions, simple facts, or basic coding help feels instant. The model doesn't waste time on questions that don't need deep analysis.

For developers using the API, this translates to lower latency in applications. AI insurance BPO Pace tested the model and said their agents run "50% faster on GPT-5.1 while exceeding accuracy of GPT-5 and other leading models."

The speed gains don't come at the cost of quality. GPT-5.1 maintains accuracy while responding faster to simple queries.

Improved Coding Performance

GPT-5.1 delivers major upgrades for programmers and developers. The model generates higher-quality code, provides better suggestions, and handles complex coding tasks more effectively.

OpenAI worked closely with startups like Cursor, Cognition, Augment Code, Factory, and Warp to improve GPT-5.1's coding personality, steerability, and code quality. This collaboration with real coding tools helped make the model more practical for actual development work.

The model is more communicative as it completes coding tasks. It provides user-facing updates so you understand what it's doing. This makes collaboration smoother when you're working through complex programming challenges.

GPT-5.1 also introduces two new developer tools in the API:

apply_patch tool: Designed to edit code more reliably. Instead of rewriting entire functions, the model can make targeted changes to specific parts of your codebase.

shell tool: Lets the model run shell commands directly. This enables more powerful automation and testing workflows.

For long-running coding projects, OpenAI released specialized models called gpt-5.1-codex and gpt-5.1-codex-mini. These models are optimized for agentic coding tasks where the AI needs to work through complex problems over extended periods.

Extended Prompt Caching for Developers

Developers using the API get access to extended prompt caching with up to 24-hour cache retention. This feature dramatically reduces costs and improves response times for repeated queries.

Prompt caching stores parts of your request so the model doesn't have to reprocess them every time. If you're building an application that repeatedly uses similar context, this can cut your API costs in half.

Extended prompt caching drives faster responses for follow-up questions at a lower cost. The 24-hour retention window means your cache stays active throughout the workday, making it practical for real applications.

Priority Processing customers also experience noticeably faster performance with GPT-5.1 compared to GPT-5. This makes the model more viable for customer-facing applications where speed matters.

Real-World Performance Gains

Companies testing GPT-5.1 report significant improvements across different use cases.

Balyasny Asset Management said GPT-5.1 "outperformed both GPT-4.1 and GPT-5 in our full dynamic evaluation suite, while running 2-3x faster than GPT-5." These speed gains apply to tool-heavy reasoning tasks where the model needs to use multiple functions and process complex data.

The token efficiency improvement is particularly valuable for businesses running AI at scale. Using half as many tokens means your budget goes twice as far, or you can handle twice as many users for the same cost.

For automation workflows, the speed improvements make GPT-5.1 more practical for customer-facing applications. Users don't want to wait 10 seconds for a simple answer. GPT-5.1's adaptive reasoning ensures fast responses when speed matters and thorough analysis when accuracy matters.

Clearer Technical Explanations

GPT-5.1 Thinking makes technical topics more accessible. The model uses less jargon and defines terms more clearly when explaining complex concepts.

This improvement helps when you're learning new topics or working through difficult problems. Instead of getting responses filled with technical terms you don't understand, GPT-5.1 explains things in clearer language.

The model still maintains its advanced reasoning capabilities. It just communicates those insights in a way that's easier to understand. This makes the most powerful model more approachable for everyone, not just experts.

When explaining technical concepts at work or helping with complex tasks, GPT-5.1 Thinking provides responses that are both accurate and understandable.

How to Use GPT-5.1 Right Now

GPT-5.1 is rolling out to paid ChatGPT users first. If you have a Pro, Plus, Go, or Business plan, you can start using it today. The rollout happens gradually over several days to keep performance stable.

Free users will get access after the initial rollout completes. Enterprise and Education customers get a seven-day early access toggle that's off by default.

To check if you have access, look for GPT-5.1 in your model selector. You'll see options for GPT-5.1 Instant and GPT-5.1 Thinking. You can also use GPT-5.1 Auto, which automatically routes your questions to the best model.

GPT-5 will remain available in the legacy models dropdown for three months. This gives you time to compare the models and adapt your workflows. OpenAI learned from the GPT-5 launch that users need transition time when models change.

For API developers, GPT-5.1 is available now on all paid tiers. The pricing and rate limits match GPT-5, so there's no cost increase for the upgrade.

Seven Prompts to Test GPT-5.1

Here are specific prompts that showcase GPT-5.1's new capabilities:

1. "Plan a birthday party for a 10-year-old who loves Pokémon — keep it under $100." Use Thinking mode for this. The model will give you detailed, budget-conscious planning with creative ideas.

2. "Summarize this URL in a friendly, quirky tone with emojis: [paste article link]" Try Instant mode with custom tone turned on. You'll see the personality controls in action.

3. "Rewrite this paragraph to sound more professional but still warm." This tests the improved instruction following and tone control. Paste your writing and watch GPT-5.1 adjust the style precisely.

4. "Explain quantum entanglement to a 12-year-old." This showcases the clearer technical explanations with less jargon.

5. "Debug this Python code: [paste code]" Test the improved coding performance and see how the model communicates as it solves the problem.

6. "What's the best way to learn Spanish in 6 months?" Use Thinking mode to see how the model handles multi-step planning and gives comprehensive advice.

7. "Give me 5 creative marketing ideas for a small coffee shop." Try this with the Quirky personality preset to see the warmer, more creative tone.

What This Means for Regular Users

If you use ChatGPT for everyday tasks, GPT-5.1 will feel noticeably better. Conversations flow more naturally. The model understands your instructions better. Responses feel more helpful and less robotic.

The personality controls let you shape ChatGPT to match your preferences. If you prefer direct, no-nonsense answers, use the Efficient preset. If you want a warmer, more supportive experience, try Friendly mode.

The adaptive reasoning means you get fast answers when you need speed and thorough answers when you need accuracy. You don't have to think about which model to use. ChatGPT handles that automatically.

For students, professionals, and creative workers, GPT-5.1 becomes a more versatile assistant that adapts to different contexts. It can be professional for work emails and playful for creative brainstorming.

What This Means for Developers

GPT-5.1 is a significant upgrade for anyone building AI applications. The combination of speed improvements, extended caching, and new developer tools makes the model more practical for production use.

The apply_patch and shell tools enable more sophisticated coding agents. Your applications can edit code more reliably and execute commands as needed. This opens up new possibilities for automated development workflows.

Extended prompt caching with 24-hour retention makes it economically viable to build applications with rich context. You can include more background information in your prompts without worrying about token costs.

The 2-3x speed improvement on everyday tasks means better user experiences in customer-facing applications. Users get faster responses without sacrificing quality.

The improved instruction following reduces the need for complex prompt engineering. Your prompts can be simpler and more direct, and the model will still do what you ask.

Safety and Responsible AI

OpenAI published a system card addendum detailing their safety approach for GPT-5.1. The core safety frameworks from GPT-5 remain in place, with additional evaluation specifically for the new features.

The company tested to ensure the warmer, more conversational tone doesn't compromise appropriate boundaries. Making AI more personable shouldn't mean it forgets important safety guidelines.

They validated that adaptive reasoning doesn't introduce new risks. Varying thinking time based on query difficulty could theoretically create new vulnerabilities, but testing showed this wasn't an issue.

The personalization features underwent scrutiny to prevent misuse or harmful outputs. Letting users customize personality raises questions about potential abuse, but the controls have appropriate guardrails.

The new developer tools (apply_patch and shell) received security evaluations. Giving AI the ability to edit code and run commands requires careful safety measures.

OpenAI emphasizes that making AI more flexible and capable requires additional vigilance. Each new feature gets evaluated for potential safety implications.

GPT-5 Legacy Models Remain Available

OpenAI learned from the GPT-5 launch that users need transition time. When GPT-5 first launched, the company planned to discontinue legacy models immediately. Users pushed back hard, and OpenAI reversed course.

This time, GPT-5 (both Instant and Thinking) will remain available in the legacy models dropdown for paid subscribers for three months. This gives you time to compare performance and adapt your workflows gradually.

You can test GPT-5.1 while keeping GPT-5 as a backup. If something works better in the older model, you can still use it. After three months, GPT-5.1 becomes the only option.

This transition period doesn't affect other legacy models. If you've been using GPT-4 or earlier models, those remain available according to their own deprecation schedules.

The Bigger Picture

GPT-5.1 represents OpenAI's focus on user experience over raw performance metrics. Unlike previous launches that emphasized benchmark scores and capability gains, this release prioritizes making AI more pleasant and practical to use.

The emphasis on conversational tone, personality controls, and improved instruction following shows OpenAI responding to user feedback. People don't just want smarter AI. They want AI that's easier and more enjoyable to work with.

The technical innovations like adaptive reasoning deliver real value without requiring users to understand the underlying technology. You don't need to know how adaptive reasoning works. You just experience faster responses and better resource allocation.

For developers, the API improvements focus on practical concerns like speed, cost, and reliability. These aren't flashy features, but they matter more for production applications than benchmark performance.

OpenAI is also learning to handle transitions better. The three-month overlap period for GPT-5 shows the company listening to user concerns about sudden changes.

Getting Started with GPT-5.1

If you're a paid ChatGPT user, check your model selector to see if GPT-5.1 is available. The rollout is gradual, so you might not see it immediately. Within a few days, all paid users should have access.

Once you have access, start by trying both Instant and Thinking modes to see how they differ. Pay attention to response times and quality. Notice how the model allocates thinking time based on your questions.

Experiment with the personality controls. Open the "Customize ChatGPT" menu and try different presets. See which tone feels most natural for your needs. Adjust the experimental sliders to fine-tune the experience.

If you're a developer, start testing the API with your existing applications. The pricing and rate limits match GPT-5, so you can upgrade without changing your billing setup. Try the extended prompt caching to see how much you can save on repeated queries.

For both users and developers, the key is experimentation. GPT-5.1 offers more flexibility than previous models. The best way to discover what works for you is to try different approaches and see what feels right.

Conclusion

GPT-5.1 makes ChatGPT smarter, faster, and more natural to use. The adaptive reasoning technology ensures you get quick answers for simple questions and thorough analysis for complex problems. The warmer conversational tone makes interactions feel more human and less robotic.

The personality controls give you unprecedented ability to shape how ChatGPT responds. Whether you want professional, friendly, quirky, or efficient responses, you can customize the experience to match your preferences.

For developers, the combination of speed improvements, extended caching, and new tools makes GPT-5.1 more practical for production applications. The model runs faster on everyday tasks while maintaining frontier intelligence for complex problems.

GPT-5.1 represents OpenAI's commitment to making AI that's both highly capable and genuinely practical to use. The improvements address real user feedback about naturalness, instruction following, and ease of use.

Try GPT-5.1 today and experience the difference. Whether you're having casual conversations, working on complex projects, or building AI applications, you'll find GPT-5.1 more helpful and easier to work with than previous models.