# Claude Opus 5.5 vs o3

> Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 47.4 on the Noometry Index. o3 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-o3
- 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 9 categories and o3 in 1 category; 10 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Opus 5.5 leads 79.5 to 32.1.
- The biggest single-benchmark swing is ARC-AGI-2: 92.5% for Claude Opus 5.5 and 6.5% for o3.
- o3 is cheaper at $2 / $8 per million input/output tokens, against $4 / $20 for Claude Opus 5.5.
- Claude Opus 5.5 accepts more context: 1M tokens versus 200K.

## Snapshot

| | Claude Opus 5.5 | o3 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 68.5 | 47.4 |
| Rank | 3 | 53 |
| Context | 1M | 200K |
| Input $/M | $4 | $2 |
| Output $/M | $20 | $8 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Opus 5.5: 71.4 (#1)
- o3: 47.3 (#57)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| LMArena Coding | 1545 | 1408 |
| SWE-bench Verified | — | 62.3% |
| FrontierCode | 54.4% | — |
| SWE-bench Verified (bash only) | — | 58.4% |
| Aider Polyglot | — | 81.3% |
| CursorBench | 57.8% | — |
| LMArena WebDev | 1820 | — |
| FrontierSWE | 62.3% | — |
| SciCode | 66.9% | — |
| GSO | — | 8.8% |
| WeirdML | — | 52.4% |
| MirrorCode | 77.4% | — |
| CadEval | — | 74% |
| ALE-Bench | — | 933.55 |

## Agentic & Tool Use

- Claude Opus 5.5: 45.3 (#13)
- o3: 34.3 (#42)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| APEX-Agents | 73.5% | — |
| Berkeley Function Calling Leaderboard | — | 63% |
| GDPval | — | 30.8% |
| DeepResearch Bench | — | 45.2% |
| OSWorld | — | 23% |
| GDP.pdf | 30.6% | — |
| LMArena Search | — | 1144 |
| METR Time Horizons | — | 65.4% |

## Reasoning

- Claude Opus 5.5: 79.5 (#2)
- o3: 32.1 (#66)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| ARC-AGI-2 | 92.5% | 6.5% |
| ARC-AGI-1 | 97.5% | 60.8% |
| CritPt | 31.7% | 1.4% |
| LMArena Hard Prompts | 1545 | 1402 |
| Mystery Game Puzzles | 71% | 29% |
| DTBench | 98.9% | 84.8% |
| LMCA | 68.2% | 39.7% |
| SimpleBench | — | 53.1% |
| Kagi LLM Benchmark | — | 67.6% |
| NYT Connections (extended) | 88.5% | — |
| Chess Puzzles | — | 38% |
| EnigmaEval | — | 13.1% |
| EBR-Bench | 71.4% | — |
| Epoch Capabilities Index | — | 146.88 |
| ForecastBench | — | 62.5 |

## Math

- Claude Opus 5.5: 92.4 (#2)
- o3: 48.9 (#49)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 91.2% | 33.3% |
| OTIS Mock AIME 2024-2025 | 100% | 84.4% |
| FrontierMath Tier 4 | 95% | — |
| ProofBench | 100% | — |
| Omni-MATH | — | 71.4% |
| LMArena Math | — | 1426 |
| MATH Level 5 | — | 97.8% |
| FrontierMath (Feb 2025 set) | — | 18.7% |
| FrontierMath Tier 4 (v1) | — | 2.1% |

## Knowledge

- Claude Opus 5.5: 66.6 (#9)
- o3: 54.5 (#47)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| GPQA Diamond | 90.6% | 81.8% |
| SimpleQA Verified | 72.2% | 49.4% |
| LMArena Expert | 1564 | 1403 |
| Humanity's Last Exam | — | 20.3% |
| MMLU-Pro | — | 85.9% |
| Confabulations | — | 14.4% |
| GPQA (HELM) | — | 75.3% |

## Multimodal

- Claude Opus 5.5: 56.5 (#2)
- o3: 40.7 (#35)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| LMArena Vision | — | 1214 |
| GeoBench | — | 74% |
| VPCT | — | 52% |
| Furniture Assembly | 83.3% | — |

## Multilingual

- Claude Opus 5.5: 59.8 (#1)
- o3: 51.9 (#99)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| LMArena Non-English | 1513 | 1402 |
| LMArena Chinese | 1572 | 1438 |
| LMArena Russian | 1532 | 1407 |
| LMArena French | — | 1430 |
| LMArena German | — | 1420 |
| LMArena Japanese | — | 1404 |
| LMArena Korean | — | 1371 |
| LMArena Spanish | — | 1395 |

## Instruction Following

- Claude Opus 5.5: 80.1 (#2)
- o3: 73.0 (#122)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| LMArena Instruction Following | 1535 | 1368 |
| IFEval | — | 86.9% |

## Long Context

- Claude Opus 5.5: 47.3 (#18)
- o3: 53.2 (#6)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| LMArena Longer Query | 1540 | 1372 |
| Fiction.LiveBench | — | 88.9% |
| CL-bench | — | 17.8% |

## Writing & Preference

- Claude Opus 5.5: 78.7 (#3)
- o3: 63.7 (#62)

| Benchmark | Claude Opus 5.5 | o3 |
|---|---|---|
| LMArena Text | 1518 | 1410 |
| LMArena Creative Writing | 1538 | 1359 |
| EQ-Bench Creative Writing | 2050 | 1676 |
| LMArena Multi-Turn | 1520 | 1405 |
| Short-Story Creative Writing | — | 83.9% |
| WildBench | — | 86.1% |

## FAQ

### Is Claude Opus 5.5 better than o3?

Claude Opus 5.5 is the stronger model overall, scoring 68.5 to 47.4 on the Noometry Index. o3 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 o3?

o3 is cheaper. It lists at $2 per million input tokens and $8 per million output tokens; Claude Opus 5.5 lists at $4 and $20.

### Is Claude Opus 5.5 or o3 better for coding?

Claude Opus 5.5 scores higher on coding benchmarks: 71.4 versus 47.3 in the Noometry coding category.

### Which has the bigger context window?

Claude Opus 5.5 does, with 1M tokens against 200K.

### How many benchmarks do Claude Opus 5.5 and o3 share?

22 benchmarks have published results for both models. Claude Opus 5.5 has 35 scored results on Noometry and o3 has 63.