OpenAI expands access to GPT-5.6 Luna for free ChatGPT users

OpenAI is expanding access to its latest GPT-5.6 model family, with GPT-5.6 Luna being rolled out to Free and Go users as part of the company’s effort to make more advanced AI capabilities available at lower cost.

According to OpenAI, GPT-5.6 Luna is the fastest and most affordable model in the GPT-5.6 family, designed for high-volume and cost-sensitive workloads. The company describes GPT-5.6 Sol as its flagship model and Terra as a balanced option for everyday work.

OpenAI’s latest ChatGPT update also introduces a Think button for Free and Go users, allowing them to use GPT-5.6 Luna for more demanding questions. The feature is being rolled out gradually and is intended to give users access to additional reasoning for complex requests.

For paid users, OpenAI has introduced more control over reasoning. Eligible Plus and Pro users can adjust how much reasoning GPT-5.6 Sol applies to a task through the model’s reasoning controls. The available options vary by subscription plan.

The GPT-5.6 family represents OpenAI’s latest push to improve the balance between AI capability, speed and cost. OpenAI says Luna delivers strong performance at a significantly lower cost than its flagship model, making it particularly suitable for applications where large volumes of AI interactions are required.

However, OpenAI has not announced that regular ChatGPT Free users can engage in completely unlimited text conversations without usage limits. Current official documentation says ChatGPT continues to operate under plan-specific usage limits, while GPT-5.6 is being rolled out progressively across eligible products and plans.

The expansion of GPT-5.6 Luna nevertheless marks a significant step in OpenAI’s strategy to make more capable AI available to a broader user base while maintaining different levels of performance, reasoning and access across its subscription tiers.