GPT-6 Luna
GPT-6 Luna
The cheap end of GPT-6, and the model free ChatGPT users now talk to.
Updated
The read
Luna is OpenAI's efficiency tier, priced at ten cents per million input tokens with a million-token window and the same structured-output discipline as the rest of the family. Since 7 October it is also what free ChatGPT users get, so for a great many people this model is now what ChatGPT means. It costs half of what GPT-5.6 Luna did for slightly better benchmark scores. Deep reasoning is not its job.
Where it shines
- Ten cents per million input tokens, and a cent for cached input
- The model behind free ChatGPT since October
- Same tool-calling and structured-output behaviour as its larger siblings
Worth knowing first
- Reasoning depth falls away quickly on multi-step problems
- Rated slightly lower than GPT-5.6 Luna by human voters
Index score
84.9
Provisional. This score is read from the product's public capability, not from the one-prompt rebuild the fully reviewed entries went through, so treat it as a placing rather than a verdict.
- Rank
- 22 of 73
- Builds
- LLMs
- Category
- Small and fast
- Output
- Text and code over an API
- Pricing
- Paid only
- Best for
- High-volume calls where cost per answer matters most
Scores are our own editorial judgement, weighted craft 55, speed 10, control 15 and value 20.
Compare it with
Also worth a look
Full index- 11Claude Haiku 5.5Claude Haiku 5.5ProvisionalA small model priced like a rounding error that scores where mid-tier models did last quarter.Small and fastPaid only87.9
- 30GPT-5.6 LunaGPT-5.6 LunaProvisionalStill cheap and still capable, but GPT-6 Luna costs half as much.Small and fastPaid only83.0
- 49Mistral Small 4Mistral Small 4ProvisionalThe best small open model to build a product on, and the licence has no catch.Small and fastFree tier78.1
