# Introducing GPT-6 Sol and Luna

The models cut API prices by 50% compared to GPT-5.6, costing $2/$10 per million tokens for Sol and $0.10/$0.50 for Luna.

- Available immediately in the API as gpt-6-sol and gpt-6-luna, as well as in ChatGPT Work and Codex for paid tiers.
- Free and Go users can access GPT-6 Luna in the desktop app.
- Prompt caching now offers 90% discounts on cached input reads and survives changes to reasoning effort or tool availability mid-conversation.
- OpenAI added a Prompt Caching Dashboard, diagnostic tools, and explicit cache breakpoints to manage prefix caching.

## Why it matters

Developers and ChatGPT subscribers gain access to faster, lower-cost frontier models for coding and long-context agentic workflows.

## Sources

- [OpenAI: Introducing GPT-6 Sol and Luna](https://openai.com/index/introducing-gpt-6-sol-and-luna)

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Summarized by dstilled on 2026-09-22. https://dstilled.ai/story/a3fc9ab6-fab7-47e5-8f36-602821281095