OpenAI Adds GPT-6 Sol and Luna, Two Cheaper Everyday Models
The new pair sits below OpenAI's flagship GPT-6 Astra. OpenAI says they make fewer mistakes and cost half as much as the models they replace.
OpenAI launched two new AI models on September 22, called GPT-6 Sol and GPT-6 Luna. They sit one step below GPT-6 Astra, the flagship model OpenAI released earlier in September.
Two Models for Two Kinds of Work
OpenAI says both models carry over much of what makes Astra better at reasoning, facts, coding and following rules. They are tuned to be faster and cheaper.
Sol is the stronger one. It is aimed at harder jobs such as writing code. Luna is lighter and is meant for large amounts of routine work, like summing up documents or pulling details out of them.
Fewer Mistakes, Lower Prices
OpenAI claims Sol makes about half as many mistakes as the model before it on the company's own fact tests. Those are internal tests, so outside checks will tell us more.
On price, OpenAI says both models cost half of the promotional price of the GPT-5.6 versions they follow. The older GPT-5.6 Sol and Luna are still available for developers who need them.
Who Can Use Them
Both models are in OpenAI's API and in ChatGPT and Codex for people on the Plus, Pro, Business, Enterprise and Edu plans. People on the Free and Go plans can use Luna in the ChatGPT desktop app.
The launch came about 90 minutes after Anthropic released Claude Opus 5.5, TechCrunch reported.
Why It Matters
Most chat apps and AI features run on mid-level models like these, not on the most expensive flagship. When these models get cheaper and more accurate, the savings and the fewer wrong answers tend to reach everyday users fast.
Questions Readers Ask
What is the difference between Sol and Luna?
Sol is the stronger of the two and is aimed at harder tasks such as coding. Luna is lighter and faster, made for big piles of simple work like summaries.
Can I still use the GPT-5.6 versions?
Yes. OpenAI's developer post says the older GPT-5.6 Sol and Luna stay available for now.
Where This Came From
We confirmed the facts in this story against these reports. The words above are our own.
