# Claude Opus 5.5 vs GPT-5.1

> Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 48.8 on the Noometry Index. GPT-5.1 costs 2.3× less per token, which makes it the better buy when Claude Opus 5.5's lead doesn't matter for your workload.

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

## Summary

- They share 22 benchmarks with published results for both. Claude Opus 5.5 scores higher in 8 categories and GPT-5.1 in 2 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Opus 5.5 leads 92.4 to 50.3.
- The biggest single-benchmark swing is ARC-AGI-2: 92.5% for Claude Opus 5.5 and 17.6% for GPT-5.1.
- GPT-5.1 is cheaper at $1.25 / $10 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
- Claude Opus 5.5 accepts more context: 1M tokens versus 400K.

## Snapshot

| | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 68.5 | 48.8 |
| Rank | 3 | 47 |
| Context | 1M | 400K |
| Input $/M | $4 | $1.25 |
| Output $/M | $20 | $10 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Opus 5.5: 71.4 (#1)
- GPT-5.1: 46.9 (#59)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| LMArena WebDev | 1820 | 1395 |
| SciCode | 66.9% | 43.3% |
| LMArena Coding | 1545 | 1454 |
| SWE-bench Verified | — | 68% |
| FrontierCode | 54.4% | — |
| SWE-bench Verified (bash only) | — | 66% |
| CursorBench | 57.8% | — |
| FrontierSWE | 62.3% | — |
| GSO | — | 13.7% |
| WeirdML | — | 60.8% |
| LiveBench Coding | — | 72.5% |
| MirrorCode | 77.4% | — |
| ALE-Bench | — | 1,192 |

## Agentic & Tool Use

- Claude Opus 5.5: 45.3 (#13)
- GPT-5.1: 32.5 (#55)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| Terminal-Bench | — | 47.6% |
| APEX-Agents | 73.5% | — |
| DeepResearch Bench | — | 42.8% |
| GDP.pdf | 30.6% | — |
| LMArena Search | — | 1199 |
| Vending-Bench 2 | — | 1,473 |

## Reasoning

- Claude Opus 5.5: 79.5 (#2)
- GPT-5.1: 39.9 (#50)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| ARC-AGI-2 | 92.5% | 17.6% |
| ARC-AGI-1 | 97.5% | 72.8% |
| CritPt | 31.7% | 4.9% |
| LMArena Hard Prompts | 1545 | 1457 |
| Mystery Game Puzzles | 71% | 19% |
| DTBench | 98.9% | 90.1% |
| LMCA | 68.2% | 43.9% |
| SimpleBench | — | 53.2% |
| NYT Connections (extended) | 88.5% | — |
| Chess Puzzles | — | 32% |
| EnigmaEval | — | 11.2% |
| EBR-Bench | 71.4% | — |
| LiveBench Reasoning | — | 95.8% |
| LiveBench Data Analysis | — | 72.1% |
| Epoch Capabilities Index | — | 149.66 |
| ForecastBench | — | 58.1 |
| LiveBench | — | 78.8% |

## Math

- Claude Opus 5.5: 92.4 (#2)
- GPT-5.1: 50.3 (#45)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| OTIS Mock AIME 2024-2025 | 100% | 88.6% |
| FrontierMath (Tiers 1-3) | 91.2% | — |
| FrontierMath Tier 4 | 95% | — |
| ProofBench | 100% | — |
| Omni-MATH | — | 46.4% |
| LiveBench Math | — | 94.5% |
| LMArena Math | — | 1446 |
| FrontierMath (Feb 2025 set) | — | 31% |
| FrontierMath Tier 4 (v1) | — | 12.5% |

## Knowledge

- Claude Opus 5.5: 66.6 (#9)
- GPT-5.1: 50.5 (#65)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| GPQA Diamond | 90.6% | 87.6% |
| SimpleQA Verified | 72.2% | 48% |
| LMArena Expert | 1564 | 1470 |
| Humanity's Last Exam | — | 23.7% |
| MMLU-Pro | — | 57.9% |
| Vectara Hallucination Rate | — | 10.9% |
| GPQA (HELM) | — | 44.2% |

## Multimodal

- Claude Opus 5.5: 56.5 (#2)
- GPT-5.1: 44.0 (#17)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Vision | — | 1250 |
| VPCT | — | 58.7% |
| Furniture Assembly | 83.3% | — |
| LMArena Document | — | 1403 |

## Multilingual

- Claude Opus 5.5: 59.8 (#1)
- GPT-5.1: 54.0 (#51)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Non-English | 1513 | 1431 |
| LMArena Chinese | 1572 | 1495 |
| LMArena Russian | 1532 | 1435 |
| LMArena French | — | 1451 |
| LMArena German | — | 1439 |
| LMArena Japanese | — | 1453 |
| LMArena Korean | — | 1401 |
| LMArena Spanish | — | 1430 |

## Instruction Following

- Claude Opus 5.5: 80.1 (#2)
- GPT-5.1: 84.0 (#1)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Instruction Following | 1535 | 1442 |
| LiveBench Instruction Following | — | 93.3% |
| IFEval | — | 93.5% |

## Long Context

- Claude Opus 5.5: 47.3 (#18)
- GPT-5.1: 47.6 (#14)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Longer Query | 1540 | 1448 |
| CL-bench | — | 23.7% |
| CL-bench Life | — | 17.3% |

## Writing & Preference

- Claude Opus 5.5: 78.7 (#3)
- GPT-5.1: 64.7 (#53)

| Benchmark | Claude Opus 5.5 | GPT-5.1 |
|---|---|---|
| LMArena Text | 1518 | 1443 |
| LMArena Creative Writing | 1538 | 1427 |
| LMArena Multi-Turn | 1520 | 1449 |
| EQ-Bench Creative Writing | 2050 | — |
| WildBench | — | 86.3% |
| LiveBench Language | — | 80.2% |

## FAQ

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

Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 48.8 on the Noometry Index. GPT-5.1 costs 2.3× 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 GPT-5.1?

GPT-5.1 is cheaper. It lists at $1.25 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 GPT-5.1 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.4 versus 46.9 in the Noometry coding category.

### Which has the bigger context window?

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

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

22 benchmarks have published results for both models. Claude Opus 5.5 has 35 scored results on Noometry and GPT-5.1 has 63.