Earlier this month, OpenAI launched GPT-6 Astra, describing it as its most powerful and capable model to date and calling it the “world’s best model” for a range of tasks, including computer-based work and coding. The company is now expanding its GPT-6 family with updated versions of its smaller Sol and Luna models.
“GPT-6 Astra introduced a new generation of intelligence; these models extend its benefits by making that intelligence more efficient and accessible,” OpenAI said.
The original Sol and Luna models were introduced earlier this year as different tiers within OpenAI’s broader model lineup. Sol is intended for more demanding workloads, including coding and other complex tasks, while Luna is positioned for clerical and routine work. OpenAI describes Luna as being suited to “high-volume tasks with a clear goal, like summarizing documents, extracting information, or answering quick questions.”
With the latest versions, OpenAI is placing particular emphasis on improved efficiency and affordability. One of the biggest changes is a significant reduction in API pricing. The GPT-6 versions of Sol and Luna will cost half as much as their GPT-5.6 counterparts, with OpenAI attributing the lower prices to improvements in caching and inference.
The company is also claiming that the new models are more reliable when generating factual answers and make fewer mistakes during coding tasks.
“On our internal factuality evaluation, which is based on de-identified real-world conversations where users flagged mistakes by our models, GPT-6 Sol makes about half as many mistakes as its predecessor, reaching Astra-level reliability at much lower cost,” OpenAI said in its announcement.
As it has done with previous model launches, OpenAI is also comparing its newest models with offerings from its main competitor, Anthropic. The company repeatedly claims that GPT-6 Sol and Luna perform substantially better on various tasks than Anthropic’s leading models, including Fable and Opus.
The timing of the launch further highlights the intense competition between the two AI companies. Anthropic released a new version of Opus 5.5 just 90 minutes before OpenAI announced its updated Sol and Luna models.
The latest versions of Sol and Luna are now available through ChatGPT Work and Codex for most paid accounts, as well as through the ChatGPT API. Luna is also being made available through the desktop app and to Free and Go users.
OpenAI said it expects to gradually bring the new models to ChatGPT across its app and website throughout the day.
