# OpenAI updates GPT-5.6 Sol, makes Luna unlimited for free users

> OpenAI updated GPT-5.6 Sol on 6 August and made Luna free and unlimited.

*The update cuts factual errors and merges fast and reasoning modes into one model for paid users.*

By Behzad Hosseini · WireRead
Canonical: https://wireread.com/news/openai-updates-gpt-5-6-sol-makes-luna-unlimited-for-free-users

OpenAI released an updated version of GPT-5.6 Sol in ChatGPT on 6 August 2026, tuned for shorter, more direct answers and fewer factual mistakes. OpenAI said the model adjusts the level of detail to the question, uses tighter formatting and corrects users rather than simply agreeing when that would not help.

The company said that in its own tests on financial, medical and legal prompts, responses containing at least one factual error were 68% less common with GPT-5.6 Sol than with GPT-5.5 Instant. Luna showed a 62% reduction, OpenAI said. It credited the improvement to better use of the sources the model looks up. OpenAI's tests are not an independent benchmark.

For Plus and Pro subscribers, a single Sol model now handles both quick answers and deep reasoning, with a slider to control how much reasoning it applies. Free and Go users get a new "Think" button instead.

Free and Go users now get GPT-5.6 Luna as the default model, with unlimited text chats, OpenAI said. The change began rolling out on 7 August.

The model picker has moved into ChatGPT's settings menu, a change some users criticised on X.

The update applies only to ChatGPT's consumer chat product. Sol in ChatGPT Work and in Codex is unchanged, and OpenAI described the release as an updated version of GPT-5.6 rather than a new model generation. OpenAI also said it strengthened protections for users under 18, including new limits on romantic role-play.

The release comes as Anthropic leads spending on AI among businesses, according to [DataNorth](https://datanorth.ai/news/openai-updates-gpt-5-6-sol-and-gpt-5-6-luna). OpenAI is pushing quality improvements and wider free access in an effort to hold its position among consumer users.

## Key takeaways

- Factual errors fell 68% for Sol and 62% for Luna versus GPT-5.5 Instant, OpenAI said
- Plus and Pro users get one Sol model with a slider for reasoning depth
- Free and Go users now default to unlimited GPT-5.6 Luna text chats from 7 August

## Sources

- [OpenAI updates GPT-5.6 Sol in ChatGPT, Luna goes free](https://datanorth.ai/news/openai-updates-gpt-5-6-sol-and-gpt-5-6-luna) — DataNorth, 2026-08-07