# Improving GPT‑5.6 Sol in ChatGPT—and expanding access to GPT-5.6 Luna for free users

OpenAI updated GPT-5.6 Sol in ChatGPT with more reliable facts and a thought slider, and expanded GPT-5.6 Luna to free users with unlimited text chats.

- Factual errors were 62% less common with GPT-5.6 Luna and 68% less common with GPT-5.6 Sol than with GPT-5.5 Instant in an internal evaluation.
- A new slider lets Plus and Pro users choose how much thought ChatGPT puts into each response.
- Free users can tap a new Think button to access higher reasoning for harder questions.
- GPT-5.6 Luna becomes the default model for Free and Go users with unlimited text chats (subject to abuse guardrails).
- The GPT-5.6 Sol update applies only to the Chat experience, not to Work and Codex.

## Why it matters

ChatGPT's free users now get the latest model and unlimited text chats, while Plus/Pro users gain more reliable and customizable responses.

## Sources

- [OpenAI: Improving GPT‑5.6 Sol in ChatGPT—and expanding access to GPT-5.6 Luna for free users](https://openai.com/index/improving-gpt-5-6-sol-in-chatgpt)

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Summarized by dstilled on 2026-08-06. https://dstilled.ai/story/e20bb54c-aaee-4c06-b521-f50bc7d9cc0d