Anthropicclosed weightsCurrentReasoning
Claude Opus 5.5
Default coding model; thinking always on; fast mode at 2x price.
Sep 22, 2026
$4 / $20
$8
1M
Benchmark scores
| Benchmark | Score | Δ vs prior | Rank (current) | Configuration | Source |
|---|---|---|---|---|---|
Terminal-Bench 2.1 | 87.6% | #1 of 20 | leaderboard | benchlm.ai ↗ | |
Humanity's Last Exam | 67.7% | #1 of 14 | lab announcement · lab-reported | cosmicjs.com ↗ | |
ARC-AGI-2 | 91.7% | #3 of 9 | leaderboard | benchlm.ai ↗ |