# Claude Sonnet 5.5 vs Step 3

> Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 40.5 on the Noometry Index.

- Canonical page: https://noometry.com/compare/claude-sonnet-5-5-vs-step-3
- Last updated: 2026-10-11
- Shared benchmarks: 13

## Summary

- They share 13 benchmarks with published results for both. Claude Sonnet 5.5 scores higher in 9 categories and Step 3 in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Sonnet 5.5 leads 87.9 to 37.6.
- Step 3 has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| Provider | Anthropic | StepFun |
| Noometry Index | 61.9 | 40.5 |
| Rank | 10 | 149 |
| Context | 1M | — |
| Input $/M | $2 | — |
| Output $/M | $10 | — |
| Weights | Proprietary | Open |

## Coding

- Claude Sonnet 5.5: 67.3 (#6)
- Step 3: 40.1 (#147)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Coding | 1513 | 1367 |
| FrontierCode | 52.1% | — |
| CursorBench | 55.5% | — |
| LMArena WebDev | 1774 | — |
| FrontierSWE | 61.9% | — |
| SciCode | 61% | — |
| ALE-Bench | 1,819 | — |

## Agentic & Tool Use

- Claude Sonnet 5.5: 45.0 (#16)
- Step 3: —

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| APEX-Agents | 75.5% | — |

## Reasoning

- Claude Sonnet 5.5: 54.0 (#28)
- Step 3: 28.4 (#105)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Hard Prompts | 1495 | 1355 |
| Kagi LLM Benchmark | — | 62.3% |
| NYT Connections (extended) | 80.5% | — |
| CritPt | 31.4% | — |
| Mystery Game Puzzles | 65% | — |
| Epoch Capabilities Index | 165.03 | — |

## Math

- Claude Sonnet 5.5: 87.9 (#6)
- Step 3: 37.6 (#148)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Math | 1510 | 1366 |
| FrontierMath (Tiers 1-3) | 88.8% | — |
| FrontierMath Tier 4 | 80.5% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| FrontierMath Erdős | 2.9% | — |

## Knowledge

- Claude Sonnet 5.5: 66.0 (#12)
- Step 3: 36.8 (#164)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Expert | 1540 | 1333 |
| GPQA Diamond | 95.6% | — |
| SimpleQA Verified | 46.5% | — |

## Multimodal

- Claude Sonnet 5.5: 51.5 (#6)
- Step 3: 35.5 (#86)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Vision | 1289 | 1177 |
| Furniture Assembly | 75% | — |

## Multilingual

- Claude Sonnet 5.5: 55.3 (#30)
- Step 3: 46.3 (#159)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Non-English | 1452 | 1327 |
| LMArena Chinese | 1522 | 1397 |
| LMArena Russian | 1451 | 1331 |
| LMArena German | — | 1371 |
| LMArena Korean | — | 1269 |
| LMArena Spanish | — | 1371 |

## Instruction Following

- Claude Sonnet 5.5: 78.3 (#11)
- Step 3: 70.4 (#164)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Instruction Following | 1495 | 1332 |

## Long Context

- Claude Sonnet 5.5: 45.9 (#28)
- Step 3: 40.3 (#157)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Longer Query | 1498 | 1326 |

## Writing & Preference

- Claude Sonnet 5.5: 66.0 (#40)
- Step 3: 54.3 (#151)

| Benchmark | Claude Sonnet 5.5 | Step 3 |
|---|---|---|
| LMArena Text | 1471 | 1350 |
| LMArena Creative Writing | 1465 | 1321 |
| LMArena Multi-Turn | 1474 | 1341 |

## FAQ

### Is Claude Sonnet 5.5 better than Step 3?

Claude Sonnet 5.5 is the stronger model overall, scoring 61.9 to 40.5 on the Noometry Index.

### Is Claude Sonnet 5.5 or Step 3 better for coding?

Claude Sonnet 5.5 scores higher on coding benchmarks: 67.3 versus 40.1 in the Noometry coding category.

### How many benchmarks do Claude Sonnet 5.5 and Step 3 share?

13 benchmarks have published results for both models. Claude Sonnet 5.5 has 32 scored results on Noometry and Step 3 has 17.