GPT-6 Sol, Luna and 6.1 Sol: Which One to Use

Since October 8, 2026, GPT-6 runs for every ChatGPT user: paid plans get GPT-6 Sol and Free and Go users get GPT-6 Luna. Developers have four GPT-6 models to choose from, and GPT-6.1 Sol is the best value for most work.

The GPT-6 family in four lines

• GPT-6.1 Sol (September 29): $2 per million input tokens and $10 per million output tokens. Coding, agents and document work, with results close to Astra.
• GPT-6 Luna (September 22): $0.10 input and $0.50 output per million tokens. High-volume extraction and classification.
• GPT-6 Sol (September 22): $2 input and $10 output. Superseded by 6.1 Sol at the same price.
• GPT-6 Astra (September 3): $10 input and $50 output. The hardest reasoning and research tasks.

Cached input drops to $0.10 per million tokens on GPT-6.1 Sol and $0.01 on Luna, which matters for chatbots and agents that resend the same context on every call.

What's new in ChatGPT: Intelligent UI

OpenAI's October 7 update lets ChatGPT answer with interactive elements — charts, buttons, forms, small calculators or a mini game — built on the fly when a visual answer works better than text. It also starts answering while it is still thinking. With web search, GPT-6 Instant begins its answer 44% sooner on average than GPT-5.6 Instant, according to OpenAI.

The rollout started on October 7 for Plus, Pro, Business and Enterprise, and reached Free and Go on October 8.

How to use the GPT-6 models

1. In ChatGPT's Chat tab there is nothing to switch on. Ask for something visual, such as "compare these three phone plans" or "make me a budget calculator", and the answer can arrive as an interface.
2. In ChatGPT Work and Codex, paid users can pick GPT-6.1 Sol for longer coding and document tasks.
3. Through the API, call gpt-6.1-sol for most jobs and gpt-6-luna for bulk tasks. Keep Astra for the jobs Sol fails.
4. On WorkCrafter, test your prompt in the text tool against other engines before you commit an API budget to one provider.

Our tips for GPT-6

• Default to GPT-6.1 Sol: OpenAI prices it at one fifth of Astra for both input and output.
• Put repeated instructions at the start of your prompt so caching kicks in; cached reads cost 95% less than standard input on 6.1 Sol.
• Free users: Luna is fine for everyday questions, but check facts on anything important. In OpenAI's own stress tests, Luna failed to report a broken search tool far more often than Sol.
• Do not judge a model on one prompt. Run five real tasks and count the edits you had to make.

More on GPT-6 and WorkCrafter

• Claude vs GPT vs Gemini vs Mistral vs DeepSeek (2026)
• You Don't Need Six AI Subscriptions
• Claude Opus 5.5, Sonnet 5.5, Haiku 5.5: How to Choose
• See WorkCrafter pricing

Sources on GPT-6

• Introducing GPT-6 Sol and Luna — OpenAI, September 22, 2026. Prices, availability by plan, API names.
• Introducing GPT-6.1 Sol — OpenAI, September 29, 2026. 6.1 Sol, Luna and Astra prices, cached prices, broken-search-tool test, API name, Astra release date.
• GPT-6 and Intelligent UI for everyone — OpenAI, October 7, 2026. Intelligent UI, rollout dates by plan, 44% faster start.