Model comparison
Claude Opus 5.5 vs Claude Sonnet 5.5
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 60.5 on the Noometry Index. Claude Sonnet 5.5 costs 2.0× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Last verified . 15 shared benchmarks.
Summary
- They share 15 benchmarks with published results for both. Claude Opus 5.5 scores higher in 6 categories and Claude Sonnet 5.5 in 0 categories; 4 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Opus 5.5 leads 79.5 to 52.4.
- The biggest single-benchmark swing is SimpleQA Verified: 72.2% for Claude Opus 5.5 and 46.5% for Claude Sonnet 5.5.
- Claude Sonnet 5.5 is cheaper at $2 / $10 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
Side by side
| Claude Opus 5.5 | Claude Sonnet 5.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Noometry Index | 68.5 | 60.5 |
| Released | 2026-09-22 | 2026-09-28 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1M |
| Max output | 128K | 128K |
| Input $ / M tokens | $4 | $2 |
| Output $ / M tokens | $20 | $10 |
| Results tracked | 35 | 16 |
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Category by category
Coding Claude Opus 5.5 leads
Claude Opus 5.5: 71.4 (#1), Claude Sonnet 5.5: 65.5 (#6)
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| FrontierCode | 54.4% | 52.1% |
| CursorBench | 57.8% | 55.5% |
| LMArena WebDev | 1820 | 1699 |
| FrontierSWE | 62.3% | 61.9% |
| SciCode | 66.9% | 61% |
| LMArena Coding | 1545 | — |
| MirrorCode | 77.4% | — |
| ALE-Bench | — | 1,819 |
Agentic & Tool Use Too close to call
Claude Opus 5.5: 45.3 (#13), Claude Sonnet 5.5: 44.9 (#14)
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| APEX-Agents | 73.5% | 75.5% |
| GDP.pdf | 30.6% | — |
Reasoning Claude Opus 5.5 leads
Claude Opus 5.5: 79.5 (#2), Claude Sonnet 5.5: 52.4 (#29)
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| CritPt | 31.7% | 31.4% |
| Mystery Game Puzzles | 71% | 65% |
| ARC-AGI-2 | 92.5% | — |
| NYT Connections (extended) | 88.5% | — |
| ARC-AGI-1 | 97.5% | — |
| EBR-Bench | 71.4% | — |
| LMArena Hard Prompts | 1545 | — |
| DTBench | 98.9% | — |
| LMCA | 68.2% | — |
Math Claude Opus 5.5 leads
Claude Opus 5.5: 92.4 (#2), Claude Sonnet 5.5: 88.7 (#4)
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | 88.8% |
| FrontierMath Tier 4 | 95% | 80.5% |
| OTIS Mock AIME 2024-2025 | 100% | 100% |
| ProofBench | 100% | 100% |
Knowledge Too close to call
Claude Opus 5.5: 66.6 (#9), Claude Sonnet 5.5: 66.0 (#11)
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| GPQA Diamond | 90.6% | 95.6% |
| SimpleQA Verified | 72.2% | 46.5% |
| LMArena Expert | 1564 | — |
Multimodal Claude Opus 5.5 leads
Claude Opus 5.5: 56.5 (#2), Claude Sonnet 5.5: 53.2 (#5)
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| Furniture Assembly | 83.3% | 75% |
Multilingual Not comparable
Claude Opus 5.5: 59.8 (#1), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Non-English | 1513 | — |
| LMArena Chinese | 1572 | — |
| LMArena Russian | 1532 | — |
Instruction Following Not comparable
Claude Opus 5.5: 80.1 (#2), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Instruction Following | 1535 | — |
Long Context Not comparable
Claude Opus 5.5: 47.3 (#18), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Longer Query | 1540 | — |
Writing & Preference Not comparable
Claude Opus 5.5: 78.7 (#3), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Text | 1518 | — |
| LMArena Creative Writing | 1538 | — |
| EQ-Bench Creative Writing | 2050 | — |
| LMArena Multi-Turn | 1520 | — |
Frequently asked questions
Is Claude Opus 5.5 better than Claude Sonnet 5.5?
Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 60.5 on the Noometry Index. Claude Sonnet 5.5 costs 2.0× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Opus 5.5 or Claude Sonnet 5.5?
Claude Sonnet 5.5 is cheaper. It lists at $2 per million input tokens and $10 per million output tokens; Claude Opus 5.5 lists at $4 and $20.
Is Claude Opus 5.5 or Claude Sonnet 5.5 better for coding?
Claude Opus 5.5 scores higher on coding benchmarks: 71.4 versus 65.5 in the Noometry coding category.
Which has the bigger context window?
Both accept 1M tokens.
How many benchmarks do Claude Opus 5.5 and Claude Sonnet 5.5 share?
15 benchmarks have published results for both models. Claude Opus 5.5 has 35 scored results on Noometry and Claude Sonnet 5.5 has 16.