GPT-6 Sol and Luna bring the model family to lower-cost tiers

OpenAI introduced GPT-6 Sol and Luna on 22 September, following Astra earlier in the month. Its announcement positioned the models for lower-cost work and described access through ChatGPT Work, Codex and the API. The rollout did not initially include Chat. Free and Go users were offered Luna in the desktop app, while the paid plans listed in the release could access both models.

The announcement listed Sol at $2 per million input tokens and $10 per million output tokens. Luna’s rates were $0.10 and $0.50 respectively. These were launch-page API rates, not a claim about a user’s subscription bill or a permanent price guarantee. OpenAI also reported improvements in its evaluations and expanded caching. Those comparisons used specific tasks and settings. The two-model expansion gave developers more choices about where to spend compute, but a cheaper token did not establish which model would complete a particular job reliably.