ChatGPT free tier gets GPT-6 Luna under OpenAI's new rollout

OpenAI's free tier has been on a fast refresh cycle. The free plan only adopted GPT-5.6 Luna as its standard model in August 2026, and roughly two months later it is being replaced by GPT-6 Luna. That cadence is the backdrop for this update: the free tier is no longer a lagging tier that waits a long cycle for the newest model, and the Go plan now shares that same default model.

The more structural change is Intelligent UI. Rather than returning mostly prose, it lets the model choose a format for the question and combine text, images, charts and buttons — a bicycle diagram with selectable parts, a recipe with a cooking schedule, a map with stops for a trip. OpenAI says the underlying approach pairs display components with a technique that streams AI-generated content to the screen, starting the display before the whole answer is finished, so users wait less even on complex answers. A separate in-chat tool builder lets users create small utilities such as a bill splitter or a calculator for savings, or a mini-game, and run them inside the chat window.

OpenAI's internal evaluation reports that on questions requiring a web search, GPT-6 Instant started answering an average of 44％ faster than GPT-5.6 Instant. That number is an internal comparison, not an outside benchmark, and the company says it will keep expanding the kinds of screens and tools Intelligent UI can produce — so the practical value of the update is likely to hinge on how quickly those additions land and how well the format choices hold up outside OpenAI's own tests.