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HEAD TO HEAD · UPDATED NOV 6, 2026
Claude Opus 5.5 vs Claude Sonnet 5.5
Two Anthropic models, on sourced numbers only. Green marks the higher (or cheaper) value on each row; the text below only calls a lead when the gap is bigger than measurement noise.
| Claude Opus 5.5 | Claude Sonnet 5.5 | |
|---|---|---|
| Arena Elo | 1509 source ↗ | 1477 source ↗ |
| GPQA Diamond | 90.6% source ↗ | 95.6% source ↗ |
| $ per 1M in / out | $4 / $20 source ↗ | $2 / $10 source ↗ |
| Blended $ per 1M (3:1) | $8.00 source ↗ | $4.00 source ↗ |
| Context window | 1M source ↗ | 1M source ↗ |
| Output speed | 110 tok/s source ↗ | 155 tok/s source ↗ |
| Released | Sep 22, 2026 source ↗ | Sep 28, 2026 source ↗ |
| Open weights | No source ↗ | No source ↗ |
| Reasoning effort tiers | low · medium · high · xhigh · max (default: medium) | low · medium · high · xhigh · max (default: high) |
| API effort control | output_config={"effort": "low" | "medium" | "high" | "xhigh" | "max"} source ↗ | output_config={"effort": "low" | "medium" | "high" | "xhigh" | "max"} source ↗ |
| Additional benchmarks | Arena WebDev: 1810 (#1) source ↗ SWE-bench Pro: 89.9% source ↗ Terminal-Bench 4.0: 66.4% (xhigh) source ↗ GDPval-AA v2.1: 1846 source ↗ CursorBench 4.0: 57.8% at max effort, 52.5% at default source ↗ AA Intelligence Index v5.0.1: 59 source ↗ | SWE-bench Pro: 81.3% source ↗ AA Intelligence Index v5.0.1: 55 source ↗ |
| Best for (workload) | Anthropic suggests starting with Opus 5.5 for most workloads. #1 on Arena WebDev (1810); 66.4% on Terminal-Bench 4.0 at xhigh effort (Anthropic). source ↗ | Fast (155 tok/s, Artificial Analysis) and strong on science: 95.6% GPQA Diamond at max effort (Epoch AI), above Opus 5.5's 90.6%. source ↗ |
Arena Elo from the arena.ai text leaderboard as of Oct 27, 2026 source ↗. Speed measured by Artificial Analysis and varies by provider.
Which one should I use?
For high-volume work where cost matters most, Claude Sonnet 5.5 is about 2.0 times cheaper per token. For overall answer quality as rated by people in blind tests, Claude Opus 5.5 leads clearly (1509 vs 1477 Arena Elo). For hard science and analysis questions, Claude Sonnet 5.5 scores higher on GPQA Diamond (95.6% vs 90.6%). For latency-sensitive use such as live chat, Claude Sonnet 5.5 is noticeably faster (155 vs 110 tokens per second). Both are Anthropic models. Anthropic is at day 30 of a typical ~15-day gap between releases (PAST TYPICAL GAP).
Key differences from the sourced numbers
- Claude Sonnet 5.5 is the cheaper option: $4.00 vs $8.00 per 1M tokens at a 3:1 input-to-output mix (about 2.0 times less).
- Claude Opus 5.5 scores 32 Elo points higher (1509 vs 1477) on the Arena text leaderboard, where people vote on blind side-by-side answers.
- On GPQA Diamond, graduate-level science questions, Claude Sonnet 5.5 leads 95.6% to 90.6%.
- Claude Sonnet 5.5 streams output faster: 155 vs 110 tokens per second (Artificial Analysis).
- Claude Opus 5.5 pricing note: Same rate across the full 1M context window.
- Claude Sonnet 5.5 pricing note: Same rate across the full 1M context window.
Frequently asked questions
Is Claude Opus 5.5 or Claude Sonnet 5.5 better?
Claude Sonnet 5.5 is the cheaper option: $4.00 vs $8.00 per 1M tokens at a 3:1 input-to-output mix (about 2.0 times less). Claude Opus 5.5 scores 32 Elo points higher (1509 vs 1477) on the Arena text leaderboard, where people vote on blind side-by-side answers. On GPQA Diamond, graduate-level science questions, Claude Sonnet 5.5 leads 95.6% to 90.6%. Claude Sonnet 5.5 streams output faster: 155 vs 110 tokens per second (Artificial Analysis). Claude Opus 5.5 pricing note: Same rate across the full 1M context window. Claude Sonnet 5.5 pricing note: Same rate across the full 1M context window.
Which one should I use: Claude Opus 5.5 or Claude Sonnet 5.5?
For high-volume work where cost matters most, Claude Sonnet 5.5 is about 2.0 times cheaper per token. For overall answer quality as rated by people in blind tests, Claude Opus 5.5 leads clearly (1509 vs 1477 Arena Elo). For hard science and analysis questions, Claude Sonnet 5.5 scores higher on GPQA Diamond (95.6% vs 90.6%). For latency-sensitive use such as live chat, Claude Sonnet 5.5 is noticeably faster (155 vs 110 tokens per second). Both are Anthropic models. Anthropic is at day 30 of a typical ~15-day gap between releases (PAST TYPICAL GAP).
How much does Claude Opus 5.5 cost compared with Claude Sonnet 5.5?
Claude Opus 5.5 lists at $4 / $20 per 1M input/output tokens ($8.00/1M blended at 3:1). Claude Sonnet 5.5 lists at $2 / $10 per 1M input/output tokens ($4.00/1M blended at 3:1).
Facts checked Nov 5, 2026 against official sources. Every number links to its source. Spotted an error? Email [email protected].