Model comparison
Claude Sonnet 5.5 vs GPT-5.5
GPT-5.5 is the stronger model overall, scoring 63.4 to 61.9 on the Noometry Index. Claude Sonnet 5.5 costs 2.8× less per token, which makes it the better buy when GPT-5.5's lead doesn't matter for your workload.
Last verified . 30 shared benchmarks.
Summary
- They share 30 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 5 categories and GPT-5.5 in 5 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where GPT-5.5 leads 72.8 to 54.0.
- The biggest single-benchmark swing is ProofBench: 100% for Claude Sonnet 5.5 and 50% for GPT-5.5.
- Claude Sonnet 5.5 is cheaper at $2 / $10 per million input/output tokens, against $5 / $30 for GPT-5.5.
- GPT-5.5 accepts more context: 1.05M tokens versus 1M.
Side by side
| Claude Sonnet 5.5 | GPT-5.5 | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 61.9 | 63.4 |
| Released | 2026-09-28 | 2026-04-23 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 1.05M |
| Max output | 128K | 128K |
| Input $ / M tokens | $2 | $5 |
| Output $ / M tokens | $10 | $30 |
| Results tracked | 32 | 71 |
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Category by category
Coding Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 67.3 (#6), GPT-5.5: 58.2 (#17)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| FrontierCode | 52.1% | 43% |
| LMArena WebDev | 1774 | 1513 |
| SciCode | 61% | 56.1% |
| LMArena Coding | 1513 | 1494 |
| ALE-Bench | 1,819 | 1,943 |
| SWE-bench Verified | — | 80.6% |
| DeepSWE | — | 67% |
| CursorBench | 55.5% | — |
| FrontierSWE | 61.9% | — |
| GSO | — | 40.2% |
| WeirdML | — | 84.9% |
| MirrorCode | — | 10% |
Agentic & Tool Use GPT-5.5 leads
Claude Sonnet 5.5: 45.0 (#16), GPT-5.5: 50.7 (#6)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| APEX-Agents | 75.5% | 55.1% |
| Terminal-Bench | — | 84.7% |
| OSWorld 2.0 | — | 13% |
| Remote Labor Index | — | 6.3% |
| τ²-bench Banking | — | 44.6% |
| DeepResearch Bench | — | 54% |
| PostTrainBench | — | 27.2% |
| ExploitBench | — | 47.4% |
| GBAEval | — | 53.2% |
| GDP.pdf | — | 26% |
| LMArena Search | — | 1242 |
| Vending-Bench 2 | — | 7,524 |
Reasoning GPT-5.5 leads
Claude Sonnet 5.5: 54.0 (#28), GPT-5.5: 72.8 (#11)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| NYT Connections (extended) | 80.5% | 96.2% |
| CritPt | 31.4% | 27.1% |
| LMArena Hard Prompts | 1495 | 1489 |
| Mystery Game Puzzles | 65% | 56% |
| Epoch Capabilities Index | 165.03 | 159.1 |
| ARC-AGI-2 | — | 85% |
| SimpleBench | — | 69% |
| Kagi LLM Benchmark | — | 88.8% |
| ARC-AGI-1 | — | 95% |
| Chess Puzzles | — | 54% |
| EBR-Bench | — | 34.3% |
| DTBench | — | 96% |
| LMCA | — | 54.3% |
| Surface Evolver Bench | — | 88.1% |
| Bench to the Future 3 | — | 0.14 |
| ForecastBench | — | 60.6 |
Math Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 87.9 (#6), GPT-5.5: 81.7 (#11)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 88.8% | 85.3% |
| FrontierMath Tier 4 | 80.5% | 72.5% |
| OTIS Mock AIME 2024-2025 | 100% | 100% |
| ProofBench | 100% | 50% |
| LMArena Math | 1510 | 1486 |
| FrontierMath Erdős | 2.9% | 0% |
| MathArena Final-Answer Competitions | — | 94.3% |
| FrontierMath (Feb 2025 set) | — | 51.7% |
| FrontierMath Tier 4 (v1) | — | 35.4% |
Knowledge Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 66.0 (#12), GPT-5.5: 64.4 (#17)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| GPQA Diamond | 95.6% | 94% |
| SimpleQA Verified | 46.5% | 63% |
| LMArena Expert | 1540 | 1508 |
| Vectara Hallucination Rate | — | 9.3% |
Multimodal Claude Sonnet 5.5 leads
Claude Sonnet 5.5: 51.5 (#6), GPT-5.5: 46.9 (#12)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| LMArena Vision | 1289 | 1297 |
| Furniture Assembly | 75% | 44.2% |
| Blueprint-Bench 2 | — | 36.2% |
| LMArena Document | — | 1486 |
Multilingual GPT-5.5 leads
Claude Sonnet 5.5: 55.3 (#30), GPT-5.5: 56.4 (#20)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| LMArena Non-English | 1452 | 1467 |
| LMArena Chinese | 1522 | 1533 |
| LMArena Russian | 1451 | 1473 |
| LMArena French | — | 1486 |
| LMArena German | — | 1480 |
| LMArena Japanese | — | 1498 |
| LMArena Korean | — | 1460 |
| LMArena Spanish | — | 1468 |
Instruction Following Too close to call
Claude Sonnet 5.5: 78.3 (#11), GPT-5.5: 77.5 (#18)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| LMArena Instruction Following | 1495 | 1479 |
Long Context GPT-5.5 leads
Claude Sonnet 5.5: 45.9 (#28), GPT-5.5: 48.3 (#12)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| LMArena Longer Query | 1498 | 1484 |
| CL-bench Life | — | 22.2% |
Writing & Preference GPT-5.5 leads
Claude Sonnet 5.5: 66.0 (#40), GPT-5.5: 72.7 (#13)
| Benchmark | Claude Sonnet 5.5 | GPT-5.5 |
|---|---|---|
| LMArena Text | 1471 | 1472 |
| LMArena Creative Writing | 1465 | 1455 |
| LMArena Multi-Turn | 1474 | 1476 |
| EQ-Bench Creative Writing | — | 1844 |
| EQ-Bench 4 | — | 1315 |
Frequently asked questions
Is Claude Sonnet 5.5 better than GPT-5.5?
GPT-5.5 is the stronger model overall, scoring 63.4 to 61.9 on the Noometry Index. Claude Sonnet 5.5 costs 2.8× less per token, which makes it the better buy when GPT-5.5's lead doesn't matter for your workload.
Which is cheaper, Claude Sonnet 5.5 or GPT-5.5?
Claude Sonnet 5.5 is cheaper. It lists at $2 per million input tokens and $10 per million output tokens; GPT-5.5 lists at $5 and $30.
Is Claude Sonnet 5.5 or GPT-5.5 better for coding?
Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 58.2 in the Noometry coding category.
Which has the bigger context window?
GPT-5.5 does, with 1.05M tokens against 1M.
How many benchmarks do Claude Sonnet 5.5 and GPT-5.5 share?
30 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and GPT-5.5 has 71.