OpenAI Launches GPT-6 Sol and Luna With Lower Costs and Fewer Errors

OpenAI has expanded its GPT-6 model family by launching updated Sol and Luna models, with lower costs, improved efficiency, and fewer reported errors than earlier versions.

The release follows GPT-6 Astra, which OpenAI introduced earlier this month as its most advanced model in the GPT-6 generation. The company said Sol and Luna extend Astra’s capabilities by making advanced AI performance more accessible across different task types.

Two Models for Different Workloads

GPT-6 Sol is designed for more complex tasks, including software development and advanced problem-solving. GPT-6 Luna targets high-volume tasks with clearer objectives, such as summarising documents, extracting information, and answering quick questions.

OpenAI said the updated models focus heavily on efficiency and affordability. The company is reducing API pricing for the GPT-6 Sol and Luna series by half compared with the previous 5.6 series, citing improvements in caching and inference technology.

Lower Error Rates and Improved Reliability

OpenAI said the new models also improve factual accuracy and coding performance. According to the company, GPT-6 Sol produced about half as many mistakes as its predecessor in an internal factuality evaluation based on de-identified real-world conversations where users had flagged incorrect responses.

The company said this improvement brings Sol closer to Astra-level reliability while operating at a lower cost.

Competition in Advanced AI Models

OpenAI positioned the new models against competing systems from Anthropic, claiming GPT-6 Sol and Luna perform better on several tasks than Anthropic’s Fable and Opus models.

The release came shortly after Anthropic introduced an updated version of Opus 5.5, highlighting the ongoing competition between major AI companies developing advanced models.

Availability

GPT-6 Sol and Luna are now available through ChatGPT Work, Codex, and the ChatGPT API for most paid users. Luna is also being made available through the desktop app and for Free and Go users.

OpenAI said it will gradually roll out the models across the ChatGPT app and website.