GPT-5.6 Explained: Sol, Terra, and Luna (2026)
OpenAI released GPT-5.6 on July 9, 2026, after a two week limited preview that started on June 26. It is not a single model but a family of three: Sol, Terra, and Luna. This guide explains what GPT-5.6 is, how the three tiers differ, what it costs, how it compares on benchmarks, and how to actually use ChatGPT 5.6 right now.
What is GPT-5.6?
GPT-5.6 is OpenAI's newest generation of its GPT model, launched in July 2026. The big change is the naming. The number 5.6 marks the generation, while the names Sol, Terra, and Luna mark capability tiers that can each improve on their own schedule. The idea is to give people a clearer choice between intelligence, speed, and cost instead of one model that tries to do everything.
Sol, Terra, and Luna: the three tiers
Sol is the flagship. It is the most capable tier, built for hard tasks like complex coding, cybersecurity, science, and long knowledge work. There is also a Sol Pro option in ChatGPT for the highest quality on tough problems.
Terra is the balanced, everyday tier. OpenAI says it is competitive with the older GPT-5.5 while costing about half as much, which makes it the sensible default for professional writing, summarizing, analysis, and routine coding.
Luna is the fast, low cost tier. It is meant for lightweight work like drafts, simple extraction, classification, and high volume tasks where speed and price matter more than maximum intelligence.
GPT-5.6 pricing
GPT-5.6 is priced per one million tokens across the three sizes:
- Sol: $5 input, $30 output
- Terra: $2.50 input, $15 output
- Luna: $1 input, $6 output
Terra sitting at half the cost of the previous generation is the headline for most everyday users.
Benchmarks: how good is it?
On the TerminalBench 2.1 coding benchmark, GPT-5.6 Sol scored 88.8 percent and Sol Ultra reached 91.9 percent, edging past Claude Mythos 5 at 88.0 percent. OpenAI's CEO also said Sol is about 54 percent more token efficient on agentic coding tasks, which matters because efficiency lowers real world cost. Early testers have praised its reliability for everyday tasks, while some still prefer rival models for raw intelligence.
How to access ChatGPT 5.6
GPT-5.6 is available across ChatGPT, the OpenAI API, Codex, and the new ChatGPT Work agent, with rollout continuing globally.
- In ChatGPT, Plus, Pro, Business, and Enterprise users can reach Sol through medium and higher effort settings, with Sol Pro for Pro and Enterprise. Free and Go users get Terra.
- In the API, developers can call Sol, Terra, and Luna directly. The alias gpt-5.6 routes to Sol.
- It is also rolling out in tools like GitHub Copilot.
If you do not see it yet, that is normal. Rollout depends on your plan, region, and workspace settings.
What launched alongside GPT-5.6
OpenAI also introduced GPT Live 1, a new voice model that can listen and speak at the same time, and ChatGPT Work, an agent that pulls context across your connected apps and files to build documents and spreadsheets. Codex is also now merged into the ChatGPT desktop app.
Using GPT-5.6 with other models
The smart way to use any new model is to compare it against the ones you already trust. A multi model app makes that easy. Chatgbot lets you run the latest GPT models next to Claude, DeepSeek, and Grok in one interface, so you can put GPT-5.6 side by side with other top models and pick the best answer for each task, all under one subscription.
Compare the latest AI models in one app
FAQ
What is GPT-5.6? GPT-5.6 is OpenAI's July 2026 model family, made up of three tiers: Sol for the hardest tasks, Terra for balanced everyday use, and Luna for fast, low cost work.
When did GPT-5.6 come out? It was previewed on June 26, 2026 and released publicly on July 9, 2026.
What is the difference between Sol, Terra, and Luna? Sol is the most capable, Terra balances quality and cost, and Luna is the fastest and cheapest. You pick the tier that fits the task.
How much does GPT-5.6 cost? Per million tokens: Sol is $5 in and $30 out, Terra is $2.50 in and $15 out, and Luna is $1 in and $6 out.
How do I use ChatGPT 5.6? It is available in ChatGPT for paid users, plus Free and Go users on Terra, and through the OpenAI API, Codex, and ChatGPT Work. You can also compare it with other models in a multi model app like Chatgbot.