OpenAI has announced a major update to ChatGPT that expands access to its GPT-5.6 model family, giving free users a more capable default model while adding new controls and improvements for paid subscribers.
The biggest change is aimed at Free and Go users, who are getting GPT-5.6 Luna as the default model for everyday text conversations. OpenAI says these users will also receive unlimited text chats, while a new Think button will let them access higher reasoning for more difficult questions.
For Plus and Pro subscribers, OpenAI is updating GPT-5.6 Sol to make responses more reliable and focused. A new reasoning-effort slider will allow eligible users to choose how much thought ChatGPT puts into a response.
GPT-5.6 Luna Becomes the Default for Free Users
The most significant part of the August update is the expansion of GPT-5.6 Luna.
OpenAI describes Luna as the fast and cost-efficient member of the GPT-5.6 family. The model is designed for high-volume workloads while still supporting capabilities such as tool use, coding and other AI-assisted tasks through supported products.
With the latest ChatGPT update, Free and Go users receive GPT-5.6 Luna as their default model for everyday chats. This makes the newer model considerably more accessible than earlier GPT-5.6 releases, which initially focused on eligible paid plans. (OpenAI)
For everyday users, the change could mean better assistance with writing, brainstorming, summarising information, answering questions and other common ChatGPT tasks without requiring a premium subscription.
Free Users Get a New “Think” Option
OpenAI is also introducing a Think button for Free users.
The idea is straightforward: users can rely on the normal Luna experience for everyday questions, then choose Think when they want ChatGPT to spend more effort working through a challenging problem.
This could be particularly useful for:
- Complex questions
- Multi-step reasoning
- Difficult writing tasks
- Planning
- Technical questions
- Problem-solving
- More complicated research-style requests
The feature gives free users a simpler way to request additional reasoning instead of having to manually choose a more advanced model.
Unlimited Text Chats for Free and Go Users
Another major change is the expansion of text-chat access.
OpenAI says Free and Go users will receive unlimited text chats with GPT-5.6 Luna as part of the update. The rollout is being introduced alongside the model change, making the free ChatGPT experience substantially different from previous usage arrangements.
However, "unlimited" refers specifically to text chats in the announcement. Other ChatGPT features and tools can have their own limits or availability rules, so users should not assume every ChatGPT capability is unlimited.
GPT-5.6 Sol Gets Better for Plus and Pro Users
The update isn't only about free users.
OpenAI is also improving GPT-5.6 Sol, its more capable model designed for demanding work. The company says the updated Sol is intended to provide more reliable factual responses and more focused answers.
Plus and Pro users are also getting a reasoning-effort slider.
This gives users greater control over how much reasoning ChatGPT uses for a response. A lighter setting can be useful when speed matters, while a higher setting can be selected for questions that require deeper reasoning.
The approach gives paid users more control rather than forcing every request through the same reasoning level.
GPT-5.6 Luna vs GPT-5.6 Sol: What's the Difference?
The GPT-5.6 family is designed around different performance and efficiency requirements.
Feature | GPT-5.6 Luna | GPT-5.6 Sol |
Main focus | Fast, efficient everyday use | More demanding reasoning and professional work |
Free ChatGPT access | Yes, as default for Free/Go users | No |
Everyday text chats | Yes | Available to eligible paid users |
Reasoning control | Think option for Free users | Reasoning-effort slider for eligible paid users |
Position in GPT-5.6 family | Cost-efficient model | Flagship model |
Typical use | Everyday questions, writing, assistance | Complex work, research, coding and reasoning |
OpenAI's model documentation describes Luna as optimized for cost-sensitive, high-volume workloads, while its GPT-5.6 materials position Sol as the flagship model for more complex work. (OpenAI Developers)
Why This Update Matters
The latest changes could significantly alter the experience for people using ChatGPT without a paid subscription.
Previously, access to OpenAI's newest and most capable models was more closely tied to paid plans. By making GPT-5.6 Luna the default for Free and Go users, OpenAI is putting a newer model into the hands of a much broader audience.
For students, content creators, professionals and casual users, the practical impact could be noticeable in everyday tasks such as:
- Writing and editing
- Brainstorming
- Learning and explanations
- Coding assistance
- Summarisation
- Planning
- Research preparation
- Content creation
The new Think option is particularly interesting because it gives free users an easy way to request more reasoning when a normal response isn't enough.
What About GPT-5.5?
The August update also changes the role of earlier models.
OpenAI's August update says the new GPT-5.6 models replace GPT-5.5 Instant in the relevant ChatGPT experience.
This means users may notice changes in response style, model availability and the options shown in the ChatGPT interface as the rollout progresses.
OpenAI has also been gradually changing how GPT-5.6 models are presented across ChatGPT, Codex, Work and the API, so availability can differ depending on the product and subscription plan.
Is GPT-5.6 Luna Available to Everyone Immediately?
OpenAI says the update is rolling out starting now, but availability can still depend on the rollout and product.
Free and Go users are the main beneficiaries of the new Luna experience in standard ChatGPT, while GPT-5.6 Sol remains associated with eligible paid plans for standard ChatGPT conversations. (OpenAI)
Users who don't immediately see a particular option may need to wait for the rollout to reach their account.
What the Update Means for ChatGPT Users
For Free users, the biggest takeaway is clear: GPT-5.6 Luna becomes the default model for everyday text conversations, accompanied by expanded access and a new Think option.
For Go users, the update brings the same Luna-focused everyday experience alongside their existing plan benefits.
For Plus and Pro users, the focus is different. The updated GPT-5.6 Sol and reasoning-effort controls are designed to provide more control over response quality and reasoning depth.
Overall, OpenAI is moving toward a more differentiated ChatGPT experience: Luna handles fast, everyday interactions for a much broader audience, while Sol provides a higher-capability option for more demanding work.
Also Read: ChatGPT Shortcut Codes & Prompt Shortcuts: The Ultimate Productivity Guide for Professionals (2026)
Final Verdict
OpenAI's latest ChatGPT update is significant because it expands access to the GPT-5.6 family beyond premium users. Making GPT-5.6 Luna the default for Free and Go users, together with expanded text-chat access and the new Think option, gives free users more capable AI assistance without requiring an upgrade.
At the same time, Plus and Pro users receive improvements to GPT-5.6 Sol and greater control over reasoning effort.
The result is a clearer division between fast everyday AI assistance and deeper reasoning, while making newer GPT-5.6 technology available to a much wider ChatGPT audience.