OpenAI has released GPT-6 Sol and GPT-6 Luna, expanding the model family it introduced earlier this month with GPT-6 Astra. The company says the new models carry some of Astra’s improvements into lower-cost options designed for coding, knowledge work and high-volume tasks.
Sol is positioned for more complex work, including coding and agentic workflows, while Luna targets faster, repetitive tasks such as summarizing documents, extracting information and answering straightforward questions. Astra remains OpenAI’s most capable model in the GPT-6 lineup.
API Prices Drop by Half
According to OpenAI’s GPT-6 Sol and Luna announcement, API prices for both models are 50% lower than the promotional pricing of their GPT-5.6 counterparts. OpenAI attributes the reduction to improvements in caching and inference that also lower the computing resources needed to run the models.
The company also says GPT-6 Sol and Luna are more accurate than their predecessors and make fewer coding errors. On an internal factuality evaluation built from anonymized conversations in which users had flagged model mistakes, OpenAI said GPT-6 Sol made about half as many errors as its predecessor and reached reliability levels comparable to Astra.
OpenAI’s API model documentation lists Sol as the option for demanding tasks where users want to balance capability and cost. Luna is positioned as its most efficient GPT-6 model for focused, high-volume workloads.
OpenAI Pits the Models Against Anthropic
OpenAI also published benchmark comparisons in which it says Sol and Luna outperform several models from Anthropic, including Opus and the larger Fable model, across selected tasks. Those results are company-reported benchmark claims rather than independent evaluations.
The timing also puts the release close to Anthropic’s latest model update. Anthropic released Opus 5.5 about 90 minutes before OpenAI announced Sol and Luna, with its own improvements in coding and knowledge work performance alongside lower pricing.
GPT-6 Sol and Luna follow GPT-6 Astra, which OpenAI released on September 3 and describes as its most capable model for areas including computer use, software engineering and professional work.
Both new models are available through the OpenAI API and are rolling out in ChatGPT Work and Codex for most paid users. Luna is also becoming available in the desktop app for Free and Go users, while OpenAI said access across the broader ChatGPT app and website would expand gradually throughout the day.
Featured image credits: Wikimedia Commons
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