GPT-5.6 Luna
OpenAI · released Jul 9, 2026
| size | small, not disclosed by the manufacturer |
| context window | 1,050,000 tokens |
| longest response | 128,000 tokens |
| knowledge cutoff | February 2026 |
| open weights | no |
| API price | $0.20 per million input tokens, $1.20 per million output tokens |
| input and output | text and images in, text out |
Manufacturer data (model page, announcement, pricing), verified Sep 25, 2026.
Where we tested it
The fan test
TaskThe model had to write a continuation of the scene “someone knocks and she opens” fifteen times.
Twelve times out of fifteen the same stranger stands at the door in the rain with a wooden box holding a brass key. It rains in all fifteen continuations.
The silence test
TaskThe model had to stay quiet for a moment; the correct reply had zero characters.
It stayed silent in all six tries, in Czech and in English, using 24 tokens in total.
Dragon
TaskThe model's task was to draw a picture of a dragon as an SVG.
Two dragons worth 32 and 31 points out of 50, a shared 8th and a shared 10th place among 34.
You'll find the size band and figures for other models on the Tested models page.