OpenAI: GPT-5.1 Chat

OpenAIID: openai/gpt-5.1-chat

GPT-5.1 Chat (AKA Instant is the fast, lightweight member of the 5.1 family, optimized for low-latency chat while retaining strong general intelligence. It uses adaptive reasoning to selectively “think” on harder queries, improving accuracy on math, coding, and multi-step tasks without slowing down typical conversations. The model is warmer and more conversational by default, with better instruction following and more stable short-form reasoning. GPT-5.1 Chat is designed for high-throughput, interactive workloads where responsiveness and consistency matter more than deep deliberation.

Pricing per 1M Tokens

Input (Prompt)$1.25
Output (Completion)$10
Cache Read$0.13
Cache WriteFree
ImageN/A

Specifications

Context Length128K
Max Output Tokens16K
Input ModalitiesFile + Image + Text
Output ModalitiesText
TokenizerGPT
Instruct TypeN/A
Top Provider Context128K
Top Provider Max Output16K
ModeratedYes

Compare this model

See how OpenAI: GPT-5.1 Chat stacks up against other models.

vs OpenAI: GPT-5.4 Nanovs OpenAI: GPT-5.4 Minivs OpenAI: GPT-5.4 Provs OpenAI: GPT-5.4vs OpenAI: GPT-5.3 Chat

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Last updated: March 23, 2026

First tracked: March 23, 2026