Claude Opus 5.5
Anthropic · 2026-09-22
Basic Information
- Developer
- Anthropic
- Release Date
- 2026-09-22
- Overall Capability Index (ECI)
- 167.4
Official Video
Benchmark Scores (Epoch AI)
Each benchmark also shows the model's rank among the models evaluated.
Advanced mathematics (FrontierMath) · #3 of 30
91.2%
Reasoning through unfamiliar puzzles (ARC-AGI-2) · #2 of 30
92.5%
Factual question accuracy (SimpleQA Verified) · #4 of 30
72.2%
Bars show accuracy (%) and start at 0%.
User Vote Rankings (LMArena)
Rankings based on people's votes comparing responses from two models. Models do not appear on leaderboards where they have too few votes.
- Overall#2 of 413 · 1512
- English#2 of 413 · 1513
- Creative writing#1 of 411 · 1532
- Web development#1 of 50 · 1815
- Coding#3 of 408 · 1535
- Chinese#3 of 389 · 1583
- Math#8 of 396 · 1516
Where to Use It
Models from Anthropic are primarily available through Claude. Available models and usage limits vary by plan, so check the pricing and free access page.
Scores and rankings are reproduced directly from public sources and were not measured by this site. Model names vary slightly across sources and are matched automatically, so different versions may occasionally be mixed together.
Source: Epoch AI (CC BY 4.0) · Checked 2026-10-04 · LMArena (CC BY 4.0) · Checked 2026-10-04