GPT-6.1 Sol

GPT-6.1 Sol was introduced at OpenAI's DevDay on September 29, 2026, one week after GPT-6 Sol, as the mid-tier workhorse of the GPT-6 family. It keeps Sol's $2/$10 per-million pricing while halving cached input to $0.10, and OpenAI claims it nearly matches GPT-6 Astra's intelligence on agentic coding, computer use, and professional work — at roughly one-fifth of Astra's standard token prices. On OpenAI's own charts it beats Astra's best DeepSWE score at a fraction of the cost per task.

It ships with a 1.05M-token context window, 128K max output, and an April 30, 2026 knowledge cutoff. An Ultrafast service tier landed October 8 for latency-sensitive voice and coding agents. Two migration gotchas: the none reasoning effort level is gone, and Chat Completions no longer supports tool calling — agentic work should use the Responses API. As with all vendor launches, the benchmark figures are OpenAI's own.