OpenAI launches GPT-5.6 series with three tiers from flagship to budget

OpenAI just dropped the GPT-5.6 series, now live in ChatGPT, Codex, and API. There are three models: flagship Sol at $5 per million tokens input and $30 output, balanced Terra at $2.5 input and $15 output, and budget-friendly Luna at $1 input and $6 output.

OpenAI says Sol is its most powerful model yet, with a new Max reasoning mode and Ultra mode that uses sub-agents for complex tasks. In coding benchmark Terminal-Bench 2.1, Sol scored 88.8% in standard mode, beating Claude Mythos 5's 88.0%, and hit 91.9% in Ultra mode. Microsoft CEO Satya Nadella says Copilot Chat, Cowork, M365 apps, GitHub, and Foundry now all support GPT-5.6.