Intelligence index
Outperforms 100% of compared models

Claude Opus 5.5 is Anthropic's flagship model for demanding reasoning, coding, and long-horizon agentic work, succeeding Claude Opus 5. It is particularly strong at multi-step changes in large codebases, code review and bug finding, financial and scientific analysis, and reading dense charts, diagrams, and screenshots, and it is more careful than its predecessor about only stating figures and citing sources it can back up.
The model completes comparable tasks in fewer steps and with fewer tokens than Opus 5, and reports on its work in plainer language, with clear updates on what it did, what it found, and what it needs from the user. Thinking is always adaptive, so effort is the main lever for trading off depth, latency, and cost, and lower effort settings remain effective for latency-sensitive workloads.
Outperforms 100% of compared models
Elo scores and win rates across design and agent tasks.
1468Elo
Win rate 65%
1385Elo
Win rate 61.5%
1397Elo
Win rate 64.8%
1437Elo
Win rate 66.2%
1351Elo
Win rate 65%
1378Elo
Win rate 63.7%
1323Elo
Win rate 52.2%
1325Elo
Win rate 55.4%
1320Elo
Win rate 61.3%
1307Elo
Win rate 62.3%
1395Elo
Win rate 69.3%
1269Elo
Win rate 58.2%