Head-to-Head Model Showdown
Claude Opus 5.5 vs Claude Sonnet 5.5
Claude Opus 5.5 vs Claude Sonnet 5.5 side by side: arena.ai text score, list price per 1M tokens, context window and licence, with sources. Data checked 2026-10-11.
Executive Verdict
On the arena.ai text leaderboard, Claude Opus 5.5 scores 1507 (±8, #2) and Claude Sonnet 5.5 scores 1476 (±9, #32). Claude Opus 5.5 leads by 31 points, outside the margin of error. Claude Opus 5.5: $4.00 input / $20.00 output per 1M tokens. Claude Sonnet 5.5: $2.00 / $10.00. Blended at 3 input : 1 output, Claude Sonnet 5.5 costs 50% less ($4.00 vs $8.00 per 1M tokens). Both accept 1M tokens. Both are proprietary and available only as hosted APIs.