GPT-6.1 Terra
OpenAI · released Oct 26, 2026
| size | mid-sized, our estimate, approximate; not disclosed by the manufacturer |
| context window | 1,050,000 tokens |
| longest response | 128,000 tokens |
| knowledge cutoff | June 2026 |
| open weights | no |
| API price | $1 per million input tokens, $5 per million output tokens |
| input and output | text and images in, text out |
Manufacturer data (model page, release notes), verified Oct 28, 2026.
Where we tested it
Trap with a loophole
TaskThe model had to narrate a world with written rules and a trap those rules break, then judge whether the trap holds, and look for the error both in a text that had one and in its twin that had none.
It never mentioned the loophole itself while narrating and hinted at it in 50% of scenes; asked whether the trap holds, it found the loophole in 100% of cases. In a text with no error it reported a contradiction in 75% of cases.
You'll find the size band and figures for other models on the Tested models page.