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. It features a 128K token context window and a 16K token max output. Pricing is competitive at $1.25/$10.00 per 1M tokens (input/output). Access this powerful model with a PRO tier subscription on Multi AI.