OpenAI ships GPT-6 Sol and Luna at half the price
GitHub Blog / changelogPress kit
OpenAI launched two models on 22 September 2026: GPT-6 Sol, a balanced model for interactive and agentic coding, and GPT-6 Luna, a lightweight model for smaller, faster tasks. Both are priced at half the cost of the 5.6-series Sol and Luna they replace.
According to OpenAI, GPT-6 Sol makes about half as many mistakes as its predecessor on factuality evaluations, reaching the reliability of GPT-6 Astra, released on 3 September, at a much lower cost, and has a lower error rate on code. The new models are available in ChatGPT Work and Codex for most paid accounts and through the API; Luna also reaches free and Go users and the desktop app. GitHub made both selectable in Copilot the same day, across its editors, command line, cloud agent and mobile apps.
The release pairs a reliability claim with a price cut rather than a new capability ceiling. Anthropic released Claude Opus 5.5, also on lower prices, the same day.