OpenAI Launches ChatGPT 5.1 with Two New Modes

OpenAI just released ChatGPT 5.1, and they're taking a slightly different approach this time by giving you two versions to pick from — Instant and Thinking.

ChatGPT 5.1 Instant is built for speed. It's designed to answer faster while still keeping accuracy intact. If you're someone who asks quick questions or needs rapid-fire responses during work, this is your mode.

The Thinking model, on the other hand, takes its time. It's meant for complex problems where you'd rather wait a bit longer for a more thorough, well-reasoned answer. The Thinking model adapts its thinking time based on the complexity of your question.

Both models come with improvements in reasoning, understanding complex queries, and conversational quality. The models also showed considerable improvements on math and coding benchmarks like AIME 2025 and Codeforces.

There's also better user customization, so the AI can adapt to how you prefer to work or communicate. For example, you can now choose how the AI will respond to you by setting among these eight tone presets: Default, Friendly, Efficient, Professional, Candid, Quirky, Cynical, and Nerdy.

Plus, there's an experimental fine-tuning feature where users can adjust sliders for conciseness, warmth, scannability, and emoji frequency.

The update feels less like a flashy feature dump and more like a refinement of what ChatGPT's already good at. If you're using it daily for work, code, or research, the speed improvements alone might be worth checking out.

Source: ChatGPT Release Notes