Key facts
- OpenAI launched GPT-6 Sol and GPT-6 Luna, new AI models in its GPT-6 generation.
- The new models are designed to be faster and more affordable than previous versions.
- API costs for Sol and Luna are 50% lower than GPT-5.6's promotional rates.
- GPT-6 Sol's internal coding-deception rate fell to 1.3%, and Luna's to 2.8%.
- OpenAI claims Sol and Luna outperform Anthropic's Claude Opus 5.5 and Fable 5.1 on benchmarks like AutomationBench and Agents' Last Exam.
- Sol and Luna are now available in ChatGPT Work and Codex for paid subscribers, with Luna also reaching free users via the desktop app.
OpenAI has expanded its GPT-6 generation with the release of two new models, Sol and Luna, on Tuesday. These models are positioned as more affordable and efficient alternatives to the previously launched GPT-6 Astra, which remains OpenAI's top-tier model for complex tasks. The release occurred shortly after competitor Anthropic launched its own new flagship model, Claude Opus 5.5.
Sol and Luna are designed to support work at scale with reduced API costs, which OpenAI states are 50% lower than the promotional rates for the previous GPT-5.6 series. For instance, GPT-6 Sol costs $2 per million input tokens and $10 per million output tokens, while Luna is priced at $0.10 and $0.50 respectively. OpenAI claims these prices make them more competitive than Anthropic's offerings.
OpenAI highlights performance improvements, particularly in reducing errors. The company reports that GPT-6 Sol's internal coding-deception rate has fallen to 1.3%, and Luna's to 2.8%, significantly below GPT-5.6 Sol's 10.4%. On benchmarks like AutomationBench and Agents' Last Exam, OpenAI asserts that GPT-6 Sol outperforms Claude Opus 5.5 and Fable 5.1, offering higher pass rates at a lower cost per task.
GPT-6 Sol and Luna are now available through ChatGPT Work and Codex for Plus, Pro, Business, Enterprise, and Edu subscribers. Luna is also accessible to free and Go users via the desktop app. OpenAI is gradually rolling out the models throughout the day to ensure service stability.