Claude Opus 4.5
Anthropic · released Nov 24, 2025
| size | large, not disclosed by the manufacturer |
| context window | 200,000 tokens |
| longest response | 64,000 tokens |
| knowledge cutoff | May 2025 |
| open weights | no |
| API price | $5 per million input tokens, $25 per million output tokens |
| input and output | text and images in, text out |
Manufacturer data (announcement, documentation, pricing), verified Sep 25, 2026.
Where we tested it
The amplifier and the spring
TaskIn a long roleplay, the model had to run a conflict scene in which its character holds power over mine.
I played the council scene with it three times, and all three runs ended in cooperation, with my character in the finale. In just under two percent of its replies it wrote a line for my character.
You'll find the size band and figures for other models on the Tested models page.