Overview
- GPT-5.1 adds two variants—Instant for everyday prompts with a warmer default tone, and Thinking for adaptive, deeper reasoning on complex tasks.
- Rollout starts with paid ChatGPT plans (Pro, Plus, Go, Business) and expands to free and logged‑out users, with Enterprise and Education getting a seven‑day early‑access toggle.
- Chat style options grow to eight presets—Default, Professional, Friendly, Candid, Quirky, Efficient, Nerdy, Cynical—plus an experiment to fine‑tune traits like warmth, conciseness, scannability, and emoji use.
- OpenAI says adaptive reasoning and improved instruction following raise performance on benchmarks such as AIME 2025 and Codeforces compared with GPT-5.
- API endpoints for GPT-5.1 Instant and Thinking arrive later this week, GPT-5 Pro will be updated soon, and legacy GPT-5 models remain selectable for paid users for three months.