OpenAI Launches GPT-5.1 Instant and Thinking Models With Smarter Reasoning and Enhanced Personalisation

Highlights

• OpenAI introduced GPT-5.1 Instant and GPT-5.1 Thinking, enhancing reasoning, fluency, and personalisation for varied user interactions.
• It includes adaptive model routing, six chat styles, legacy tone modes, fine-tuning controls, and instant personalisation across chats.
• Both are available first to paid users (Pro, Plus, Go, Business) with broader access coming later.

OpenAI has officially introduced GPT-5.1, the latest update to its GPT-5 series. It brings major improvements in reasoning ability, conversational fluency, and user personalisation. The company describes GPT-5.1 as an iterative enhancement within the same generation, designed to make ChatGPT more intelligent, responsive, and adaptive to individual user needs.

The release includes two new models, GPT-5.1 Instant and GPT-5.1 Thinking. Both aimed at delivering a more natural and flexible ChatGPT experience across different types of interactions.

What Is GPT-5.1 Instant?

The GPT-5.1 Instant model is the most widely used ChatGPT variant and now features a warmer, more conversational tone. Its instruction-following capability has been refined, improving response accuracy and clarity.

With adaptive reasoning, GPT-5.1 Instant can now spend more time analysing complex prompts while keeping fast response speeds for simpler queries.

According to OpenAI’s internal testing, the model has shown significant gains in math and coding tasks, including benchmarks like AIME 2025 and Codeforces.

What is GPT-5.1 Thinking?

Built for more demanding cognitive tasks, GPT-5.1 Thinking dynamically adjusts its processing time based on the complexity of user queries. It responds faster to simple questions while providing more comprehensive answers for advanced topics.

Compared to GPT-5 Thinking, the new version is twice as fast on basic queries but takes twice as long on the most complex ones. It ensures more accurate, thoughtful responses. The model also produces clearer, less technical explanations and maintains a warmer, more empathetic tone.

GPT-5.1 – Key Features

• Adaptive Model Routing: Automatically assigns each query to the most suitable model (Instant or Thinking).
• Legacy Styles Retained: The older Cynical and Nerdy modes remain available.
• Fine-Tuning Controls: Offers customisation for conciseness, warmth, scannability, and emoji usage.
• Proactive Suggestions: ChatGPT can now suggest changes to tone or style mid-conversation.
• Instant Personalisation: Any customisation applies immediately across all active chats.
• Better Custom Instruction Handling: Provides more precise control over tone and behaviour for both models.
• Six Chat Styles: Users can choose between Default, Friendly, Efficient, Professional, Candid, and Quirky tones.

OpenAI plans to further evolve GPT-5.1 with continued enhancements to reasoning, natural dialogue, and adaptive learning. Future iterations aim to make ChatGPT even more personalised and intuitive, aligning its behaviour more closely with individual user preferences.

Availability

The rollout of GPT-5.1 Instant and GPT-5.1 Thinking begins with paid users under the Pro, Plus, Go, and Business plans. Free and logged-out users will gain access later.

Enterprise and Education subscribers have a seven-day early access toggle (off by default). Over time, GPT-5.1 will become the default ChatGPT model for all users.

Meanwhile, legacy GPT-5 models will remain accessible to paid subscribers for the next three months, ensuring a smooth transition. Both GPT-5.1 Instant and GPT-5.1 Thinking will also be integrated into the API under the names gpt-5.1-chat-latest and gpt-5.1 with full support for adaptive reasoning capabilities.

FAQs

Q1. What are GPT-5.1 Instant and GPT-5.1 Thinking models?

Answer. GPT-5.1 Instant offers fast, conversational responses with improved instruction-following, while GPT-5.1 Thinking handles complex queries with deeper reasoning and dynamic response times.

Q2. What personalisation features does GPT-5.1 include?

Answer. GPT-5.1 supports adaptive model routing, six chat styles, legacy tone modes, fine-tuning controls, proactive tone suggestions, and instant personalisation across chats.

Q3. Who can access GPT-5.1 and when?

Answer. GPT-5.1 is rolling out to paid users under Pro, Plus, Go, and Business plans first. Free and logged-out users will gain access later, with enterprise and education subscribers getting early toggle access.

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