OpenAI makes GPT-5.6 Luna the free ChatGPT default with unlimited text chats

OpenAI said on August 6, 2026 that GPT-5.6 Luna will become the default model for ChatGPT Free and Go users this week, with unlimited text-based chats subject to abuse guardrails.

The move pushes OpenAI’s free tier from capped to effectively uncapped conversation, escalating a competition among AI developers to give away more capability to hold consumers. A new “Think” button for harder questions is set to roll out the following week, though file and image uploads remain limited for free users.

For Plus and Pro subscribers, an updated GPT-5.6 Sol becomes the new default for both instant and reasoning modes, tuned to give more focused answers and cut unnecessary formatting, OpenAI said. Paid users also get a reasoning-depth slider across the web, mobile and desktop apps, letting them trade speed for more deliberate answers.

OpenAI said its internal testing on financial, medical and legal prompts found responses containing at least one factual error were 68 percent less common with the updated Sol than with the prior default, GPT-5.5 Instant. That figure comes from OpenAI’s own evaluations and has not been independently verified; the company did not detail its test set or scoring method.

Unlimited free chats put a heavier load on OpenAI’s compute at a time when inference costs remain the central expense of running consumer AI. The test worth watching is whether the free unlimited tier holds up in practice, or OpenAI quietly reintroduces limits.