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OpenAI launches cheaper GPT-6 Sol, Luna
Sol is tailored for complex tasks such as coding

OpenAI launches cheaper GPT-6 Sol, Luna

Sep 23, 2026
10:08 am

What's the story

OpenAI has expanded its GPT-6 family with the launch of improved versions of its smaller models, Sol and Luna. The new models are designed to make the advanced intelligence introduced by GPT-6 Astra more efficient and accessible. While Sol is tailored for complex tasks such as coding, Luna is better suited for clerical work like summarizing documents or answering quick questions.

Cost reduction

API access now half the cost of 5.6 series

OpenAI is also highlighting major improvements in efficiency and affordability with the new models.

The company has announced a massive price cut for API access, with the 6 series models now available at half the cost of their 5.6 series counterparts.

This price drop is attributed to improvements in caching and inference, making these advanced AI tools more accessible than ever before.

Performance boost

New models reach Astra-level reliability at lower costs

OpenAI claims its new models are better at providing factually accurate answers with fewer mistakes, especially in coding.

The company says that on its internal factuality evaluation, the GPT-6 Sol makes about half as many mistakes as its predecessor.

This means it reaches Astra-level reliability at a much lower cost.

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Competitive edge

OpenAI claims its models outperform Anthropic's top offerings

As is the case with every new model launch, OpenAI is also touting its latest offerings as better than those of its closest competitor, Anthropic.

The company claims that GPT-6 Sol and Luna perform significantly better than Anthropic's top models - Fable and Opus.

This comes as a major endorsement of the capabilities of OpenAI's latest AI tools in comparison to industry rivals.

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Availability

Availability in ChatGPT Work and Codex

The new versions of Sol and Luna are already available in ChatGPT Work and Codex for most paid accounts, as well as in the ChatGPT API.

Luna will also be available in the desktop app and for Free and Go users.

OpenAI plans to roll out these models to ChatGPT (the app and website) throughout the day, making them widely accessible to users across different platforms.

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