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Claude Opus 5.5 vs Claude Sonnet 5.5

On the 403 use cases both models ran, Claude Sonnet 5.5 won 353 to 27, with 23 tied (better outcome first, then lower cost).

Pass rate: Claude Opus 5.5 92% (411 runs) vs Claude Sonnet 5.5 87% (411 runs). Average cost per run: $0.21 vs $0.08.

MetricClaude Opus 5.5Claude Sonnet 5.5
Runs on shared use cases411411
Pass rate92% (378/411)87% (359/411)
Avg cost per run$0.21$0.08
Avg wall time3m53s
Step-ins per run0.340.30
Use cases won27353

Use case by use case

Only use cases both models ran are compared; all settings of each model are grouped. How we score.