# Claude Sonnet 5.5 vs GPT-5.1

> Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 49.0 on the Noometry Index.

- Canonical page: https://noometry.com/compare/claude-sonnet-5-5-vs-gpt-5-1
- Last updated: 2026-10-12
- Shared benchmarks: 22

## Summary

- They share 22 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 8 categories and GPT-5.1 in 2 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 52.2.
- The biggest single-benchmark swing is Mystery Game Puzzles: 65% for Claude Sonnet 5.5 and 19% for GPT-5.1.
- GPT-5.1 is cheaper at $1.25 / $10 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.5.
- Claude Sonnet 5.5 accepts more context: 1M tokens versus 400K.

## Snapshot

| | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 61.9 | 49.0 |
| Rank | 10 | 53 |
| Context | 1M | 400K |
| Input $/M | $2 | $1.25 |
| Output $/M | $10 | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Sonnet 5.5: 67.3 (#6)
- GPT-5.1: 46.4 (#66)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| LMArena WebDev | 1774 | 1395 |
| SciCode | 61% | 43.3% |
| LMArena Coding | 1513 | 1454 |
| ALE-Bench | 1,819 | 1,192 |
| SWE-bench Verified | — | 68% |
| FrontierCode | 52.1% | — |
| SWE-bench Verified (bash only) | — | 66% |
| CursorBench | 55.5% | — |
| FrontierSWE | 61.9% | — |
| GSO | — | 13.7% |
| WeirdML | — | 60.8% |
| LiveBench Coding | — | 72.5% |

## Agentic & Tool Use

- Claude Sonnet 5.5: 45.0 (#16)
- GPT-5.1: 32.7 (#60)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| Terminal-Bench | — | 47.6% |
| APEX-Agents | 75.5% | — |
| DeepResearch Bench | — | 42.8% |
| LMArena Search | — | 1199 |
| Vending-Bench 2 | — | 1,473 |

## Reasoning

- Claude Sonnet 5.5: 54.0 (#28)
- GPT-5.1: 39.8 (#58)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| CritPt | 31.4% | 4.9% |
| LMArena Hard Prompts | 1495 | 1457 |
| Mystery Game Puzzles | 65% | 19% |
| Epoch Capabilities Index | 165.03 | 149.64 |
| ARC-AGI-2 | — | 17.6% |
| SimpleBench | — | 53.2% |
| NYT Connections (extended) | 80.5% | — |
| ARC-AGI-1 | — | 72.8% |
| Chess Puzzles | — | 32% |
| EnigmaEval | — | 11.2% |
| LiveBench Reasoning | — | 95.8% |
| DTBench | — | 90.1% |
| LiveBench Data Analysis | — | 72.1% |
| LMCA | — | 43.9% |
| ForecastBench | — | 58.1 |
| LiveBench | — | 78.8% |

## Math

- Claude Sonnet 5.5: 87.9 (#6)
- GPT-5.1: 52.2 (#51)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 100% | 88.6% |
| LMArena Math | 1510 | 1447 |
| FrontierMath (Tiers 1-3) | 88.8% | — |
| FrontierMath Tier 4 | 80.5% | — |
| ProofBench | 100% | — |
| Omni-MATH | — | 46.4% |
| LiveBench Math | — | 94.5% |
| FrontierMath (Feb 2025 set) | — | 31% |
| FrontierMath Erdős | 2.9% | — |
| FrontierMath Tier 4 (v1) | — | 12.5% |

## Knowledge

- Claude Sonnet 5.5: 66.0 (#12)
- GPT-5.1: 50.6 (#71)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| GPQA Diamond | 95.6% | 87.6% |
| SimpleQA Verified | 46.5% | 48% |
| LMArena Expert | 1540 | 1470 |
| Humanity's Last Exam | — | 23.7% |
| MMLU-Pro | — | 57.9% |
| Vectara Hallucination Rate | — | 10.9% |
| GPQA (HELM) | — | 44.2% |

## Multimodal

- Claude Sonnet 5.5: 51.5 (#6)
- GPT-5.1: 44.8 (#19)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Vision | 1289 | 1250 |
| VPCT | — | 58.7% |
| Furniture Assembly | 75% | — |
| LMArena Document | — | 1403 |

## Multilingual

- Claude Sonnet 5.5: 55.3 (#30)
- GPT-5.1: 53.8 (#56)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Non-English | 1452 | 1431 |
| LMArena Chinese | 1522 | 1495 |
| LMArena Russian | 1451 | 1435 |
| LMArena French | — | 1450 |
| LMArena German | — | 1438 |
| LMArena Japanese | — | 1453 |
| LMArena Korean | — | 1401 |
| LMArena Spanish | — | 1433 |

## Instruction Following

- Claude Sonnet 5.5: 78.3 (#11)
- GPT-5.1: 83.9 (#1)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Instruction Following | 1495 | 1443 |
| LiveBench Instruction Following | — | 93.3% |
| IFEval | — | 93.5% |

## Long Context

- Claude Sonnet 5.5: 45.9 (#28)
- GPT-5.1: 47.6 (#14)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Longer Query | 1498 | 1447 |
| CL-bench | — | 23.7% |
| CL-bench Life | — | 17.3% |

## Writing & Preference

- Claude Sonnet 5.5: 66.0 (#40)
- GPT-5.1: 64.5 (#55)

| Benchmark | Claude Sonnet 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Text | 1471 | 1443 |
| LMArena Creative Writing | 1465 | 1427 |
| LMArena Multi-Turn | 1474 | 1450 |
| WildBench | — | 86.3% |
| LiveBench Language | — | 80.2% |

## FAQ

### Is Claude Sonnet 5.5 better than GPT-5.1?

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 49.0 on the Noometry Index.

### Which is cheaper, Claude Sonnet 5.5 or GPT-5.1?

GPT-5.1 is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; Claude Sonnet 5.5 lists at $2 and $10.

### Is Claude Sonnet 5.5 or GPT-5.1 better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 46.4 in the Noometry coding category.

### Which has the bigger context window?

Claude Sonnet 5.5 does, with 1M tokens against 400K.

### How many benchmarks do Claude Sonnet 5.5 and GPT-5.1 share?

22 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and GPT-5.1 has 63.