Overview
- GPT-5.1 begins a phased release today in ChatGPT, prioritizing paid tiers (Pro, Plus, Go, Business) before expanding to free users, with API access slated for later this week.
- Two options debut: GPT-5.1 Instant emphasizes a warmer tone and stronger instruction-following, while GPT-5.1 Thinking adapts its reasoning time to task complexity for clearer, more persistent answers.
- Users gain expanded personality presets such as Professional, Candid, and Quirky, plus new controls to adjust concision, warmth, and emoji use, with an in-settings style-tuning experiment rolling out to a limited group.
- GPT-5 Auto continues to route prompts to the best model by default, though users can choose models manually, and legacy GPT-5 variants remain available to paid subscribers for three months.
- OpenAI says both models add adaptive reasoning and show gains on AIME 2025 and Codeforces benchmarks, results the company reports from its internal testing.