GPT-6 Sol and Luna launched Sept. 22 with input prices of $2 and $0.10 per million tokens, available to API developers and paid subscribers of ChatGPT Work. Output tokens are priced at $10 per million for Sol and $0.50 per million for Luna, representing a 50% decrease from GPT-5.6 promotional rates. Plus, Pro, Business, Enterprise, and Edu users can access the models via ChatGPT Work and Codex, while Free and Go users have access to Luna through the desktop app.

The new models utilize GPT-6 Astra architecture with improvements to caching and inference that allow for 90% discounts on cached input-token reads. On the DeepSWE benchmark, Sol's cost per task is roughly 80% lower than Claude Fable 5's best result, while Luna is 96% cheaper per task. OpenAI reported that Sol also outperforms Claude Opus 5 on AutomationBench at 9% of the competitor's cost per task.