Earlier this month, OpenAI released the first GPT-6 model with Astra. Now GPT-6 is expanding with new GPT-6 Sol and GPT-6 Luna models. According to ChatGPT desktop app release notes, these models use fewer tokens than GPT-5.6 versions. They are rolling out to Codex and ChatGPT Work at lower token prices. Use Sol for complex coding and agentic workflows, and Luna for focused, high-volume tasks.

Both models are rolling out to Plus, Pro, Business, Enterprise, and Edu users. Free and Go users can access Luna in the desktop app. Enterprise administrators must enable the new models. In ChatGPT, they are available in Work and Codex, but not Chat. Note the absence of a GPT-6 Terra model; OpenAI is expected to drop the medium model in favor of three: Terra (small), Sol (large), and Astra (extra large).

OpenAI says GPT-6 Sol and Luna are 50% cheaper than GPT-5.6 versions. On OSWorld 2.0 offline, GPT-6 Sol at xhigh effort achieves 60.5% versus Claude Opus 5 at medium effort's 60.3%, at approximately 80% lower cost per task. GPT-6 Luna (max) exceeds GPT-5.6 Sol (medium) at one tenth of its cost.