ChatGPT Free Users Get Unlimited Text Chats and GPT-5.6 Luna — All the August 2026 Updates

GPT-5.6 Luna as the Default Model

GPT-5.6 Luna replaces GPT-5.5 Instant as the default model for Free and Go users. OpenAI describes it as a faster, more capable model that originally debuted in early July 2026 .

The "Think" Button

Free and Go users will also see a new Think button appear when they ask harder questions. Tapping it triggers higher reasoning effort on a per-message basis, subject to abuse guardrails .

What Plus and Pro Users Get

Retuned GPT-5.6 Sol

Paid subscribers get an updated version of GPT-5.6 Sol tuned for everyday ChatGPT conversations. The model now gives more direct, focused answers and avoids unnecessary formatting or irrelevant detail .

Thinking Slider

A new slider lets Plus and Pro users choose how much "thought" or reasoning effort the model applies to each response. This gives users direct control over the balance between speed and depth .

Factual Error Reduction vs. GPT-5.5 Instant

OpenAI reported two key figures from internal evaluations on financial, medical, and legal prompts :

• GPT-5.6 Luna reduces responses containing at least one factual error by 62% compared to GPT-5.5 Instant .
• GPT-5.6 Sol (retuned) reduces factual errors by 68% compared to GPT-5.5 Instant, per OpenAI's internal evaluations .

Both improvements are statistically significant and represent substantial gains in reliability for high-stakes questions involving dates, numbers, sources, legal rules, and medical information .

Availability Timeline

• GPT-5.6 Luna became the default model for Free and Go users during the week of August 6 .
• Unlimited text chats and the Think button were scheduled to roll out starting the week of August 10–13 .
• GPT-5.6 Sol retune was available for Plus and Pro users starting August 6 .