GPT-6 Sol and Luna: half the price, and about half the factual errors
2026·09·27 · 1 min read
Foto: AltumCode (@altumcode) · Unsplash
Esta entrada todavía no está traducida a este idioma — se muestra la versión original.
OpenAI cut API prices by 50% for the two lighter members of the GPT-6 family, released September 22, 2026. Sol's output dropped from $20 to $10 per million tokens.
OpenAI released GPT-6 Sol and GPT-6 Luna on September 22, 2026, lighter siblings of GPT-6 Astra trained with similar methods.
The headline is the invoice. API prices are 50% lower than the GPT-5.6 promotional pricing:
| Model | Output, per 1M tokens |
|---|---|
| GPT-5.6 Sol → GPT-6 Sol | $20 → $10 |
| GPT-5.6 Luna → GPT-6 Luna | $1.20 → $0.50 |
Luna's input price is $0.10 per million tokens. OpenAI attributes the cut to caching and inference improvements being passed through, not to a weaker model.
On quality, the number worth repeating is factuality: on OpenAI's internal evaluation — built from de-identified real conversations where users had flagged a factual error from a previous model — Sol makes about half as many mistakes as its predecessor. The company is explicit that those error-inducing conversations are not representative of typical usage.
Availability from day one: ChatGPT Work and Codex for Plus, Pro, Business,
Enterprise and Edu users; Luna in the desktop app for Free and Go users; and in
the API as gpt-6-sol and gpt-6-luna. Not in Chat yet.
Source: OpenAI, "Introducing GPT-6 Sol and Luna" (September 22, 2026).