GPT-5.6 Sol

GPT-5.6 Sol is the flagship in OpenAI's GPT-5.6 family, previewed on June 26, 2026. Pricing is $5 per million input tokens and $30 per million output, with a 1 million token context window. Access at launch is intentionally narrow: at the request of the US Government, only roughly 20 pre-approved organizations were granted entry to the limited preview, with general availability planned in the weeks that follow. OpenAI positioned Sol for frontier reasoning and agentic work and disclosed partial benchmarks (Sol Ultra at 91.9 percent on Terminal-Bench 2.1, base Sol at 88.8 percent), while holding back SWE-bench, MMLU-Pro, GDPval, and FrontierMath until GA. A Cerebras deployment running Sol at up to 750 tokens per second is planned for July. Treat Sol as a forward-looking option for now: priced, named, and benchmarked in part, but not yet broadly callable.