Model comparison
Claude Opus 4.8 vs Claude Sonnet 5.5
Claude Opus 4.8 and Claude Sonnet 5.5 score almost the same on the Noometry Index (60.7 vs 60.5), so choose on price, context window or the category you care about most.
Last verified . 14 shared benchmarks.
Summary
- They share 14 benchmarks with published results for both. Claude Opus 4.8 scores higher in 2 categories and Claude Sonnet 5.5 in 4 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Opus 4.8 leads 64.6 to 52.4.
- The biggest single-benchmark swing is Furniture Assembly: 42.5% for Claude Opus 4.8 and 75% for Claude Sonnet 5.5.
- Claude Sonnet 5.5 is cheaper at $2 / $10 per million input/output tokens, against $5 / $25 for Claude Opus 4.8.
Side by side
| Claude Opus 4.8 | Claude Sonnet 5.5 | |
|---|---|---|
| Provider | Anthropic | Anthropic |
| Noometry Index | 60.7 | 60.5 |
| Released | 2026-05-28 | 2026-09-28 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1M |
| Max output | 128K | 128K |
| Input $ / M tokens | $5 | $2 |
| Output $ / M tokens | $25 | $10 |
| Results tracked | 65 | 16 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude Opus 4.8: 60.2 (#9), Claude Sonnet 5.5: 65.5 (#6)
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| FrontierCode | 46.5% | 52.1% |
| LMArena WebDev | 1556 | 1699 |
| SciCode | 53.5% | 61% |
| ALE-Bench | 1,564 | 1,819 |
| DeepSWE | 59% | — |
| CursorBench | — | 55.5% |
| FrontierSWE | — | 61.9% |
| GSO | 47.1% | — |
| WeirdML | 82.9% | — |
| LMArena Coding | 1491 | — |
Agentic & Tool Use Claude Opus 4.8 leads
Claude Opus 4.8: 47.6 (#10), Claude Sonnet 5.5: 44.9 (#14)
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| APEX-Agents | 48.9% | 75.5% |
| OSWorld 2.0 | 20.6% | — |
| Remote Labor Index | 8.3% | — |
| τ²-bench Banking | 39.7% | — |
| DeepResearch Bench | 50.2% | — |
| PostTrainBench | 33.8% | — |
| GBAEval | 70.9% | — |
| GDP.pdf | 24% | — |
| LMArena Search | 1204 | — |
| Vending-Bench 2 | 5,787 | — |
Reasoning Claude Opus 4.8 leads
Claude Opus 4.8: 64.6 (#14), Claude Sonnet 5.5: 52.4 (#29)
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| CritPt | 20.9% | 31.4% |
| Mystery Game Puzzles | 36% | 65% |
| ARC-AGI-2 | 72.1% | — |
| SimpleBench | 64.8% | — |
| Kagi LLM Benchmark | 88.8% | — |
| NYT Connections (extended) | 91.1% | — |
| ARC-AGI-1 | 92.5% | — |
| Chess Puzzles | 34% | — |
| EnigmaEval | 23.5% | — |
| EBR-Bench | 28.6% | — |
| LMArena Hard Prompts | 1481 | — |
| DTBench | 94.9% | — |
| LMCA | 57.5% | — |
| Surface Evolver Bench | 87.5% | — |
| Bench to the Future 3 | 0.14 | — |
| Epoch Capabilities Index | 158.3 | — |
| ForecastBench | 59.9 | — |
Math Claude Sonnet 5.5 leads
Claude Opus 4.8: 78.2 (#11), Claude Sonnet 5.5: 88.7 (#4)
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 80% | 88.8% |
| FrontierMath Tier 4 | 56.1% | 80.5% |
| OTIS Mock AIME 2024-2025 | 98.3% | 100% |
| ProofBench | 69% | 100% |
| MathArena Final-Answer Competitions | 91.8% | — |
| LMArena Math | 1487 | — |
| FrontierMath (Feb 2025 set) | 47.2% | — |
| FrontierMath Tier 4 (v1) | 31.3% | — |
Knowledge Claude Sonnet 5.5 leads
Claude Opus 4.8: 61.3 (#26), Claude Sonnet 5.5: 66.0 (#11)
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| GPQA Diamond | 91% | 95.6% |
| SimpleQA Verified | 53% | 46.5% |
| LMArena Expert | 1501 | — |
Multimodal Claude Sonnet 5.5 leads
Claude Opus 4.8: 43.2 (#20), Claude Sonnet 5.5: 53.2 (#5)
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| Furniture Assembly | 42.5% | 75% |
| LMArena Vision | 1295 | — |
| Blueprint-Bench 2 | 14.5% | — |
| LMArena Document | 1475 | — |
Multilingual Not comparable
Claude Opus 4.8: 55.4 (#31), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Non-English | 1450 | — |
| LMArena Chinese | 1509 | — |
| LMArena French | 1482 | — |
| LMArena German | 1470 | — |
| LMArena Japanese | 1440 | — |
| LMArena Korean | 1432 | — |
| LMArena Russian | 1476 | — |
| LMArena Spanish | 1470 | — |
Instruction Following Not comparable
Claude Opus 4.8: 77.6 (#22), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Instruction Following | 1476 | — |
Long Context Not comparable
Claude Opus 4.8: 45.4 (#37), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Longer Query | 1482 | — |
Writing & Preference Not comparable
Claude Opus 4.8: 72.1 (#17), Claude Sonnet 5.5: —
| Benchmark | Claude Opus 4.8 | Claude Sonnet 5.5 |
|---|---|---|
| LMArena Text | 1460 | — |
| LMArena Creative Writing | 1453 | — |
| EQ-Bench Creative Writing | 1840 | — |
| EQ-Bench 4 | 1281 | — |
| LMArena Multi-Turn | 1476 | — |
Frequently asked questions
Is Claude Opus 4.8 better than Claude Sonnet 5.5?
Claude Opus 4.8 and Claude Sonnet 5.5 score almost the same on the Noometry Index (60.7 vs 60.5), so choose on price, context window or the category you care about most.
Which is cheaper, Claude Opus 4.8 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 4.8 lists at $5 and $25.
Is Claude Opus 4.8 or Claude Sonnet 5.5 better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 65.5 versus 60.2 in the Noometry coding category.
Which has the bigger context window?
Both accept 1M tokens.
How many benchmarks do Claude Opus 4.8 and Claude Sonnet 5.5 share?
14 benchmarks have published results for both models. Claude Opus 4.8 has 65 scored results on Noometry and Claude Sonnet 5.5 has 16.