# Claude Sonnet 4.5 vs Step 3

> Claude Sonnet 4.5 is the stronger model overall, scoring 44.1 to 40.5 on the Noometry Index.

- Canonical page: https://noometry.com/compare/claude-sonnet-4-5-vs-step-3
- Last updated: 2026-10-11
- Shared benchmarks: 16

## Summary

- They share 16 benchmarks with published results for both. Claude Sonnet 4.5 scores higher in 6 categories and Step 3 in 3 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Claude Sonnet 4.5 leads 66.5 to 54.3.
- Step 3 has downloadable open weights; the other is API-only.

## Snapshot

| | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| Provider | Anthropic | StepFun |
| Noometry Index | 44.1 | 40.5 |
| Rank | 81 | 149 |
| Context | 200K | — |
| Input $/M | $3 | — |
| Output $/M | $15 | — |
| Weights | Proprietary | Open |

## Coding

- Claude Sonnet 4.5: 47.3 (#61)
- Step 3: 40.1 (#147)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Coding | 1489 | 1367 |
| SWE-bench Verified | 71.3% | — |
| SWE-bench Verified (bash only) | 71.4% | — |
| LMArena WebDev | 1393 | — |
| SWE-bench Multilingual | 67% | — |
| SciCode | 44.7% | — |
| GSO | 14.7% | — |
| WeirdML | 47.7% | — |
| ALE-Bench | 796.15 | — |
| AlgoTune | 1.52 | — |

## Agentic & Tool Use

- Claude Sonnet 4.5: 38.3 (#32)
- Step 3: —

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| Terminal-Bench | 46.5% | — |
| Berkeley Function Calling Leaderboard | 73.2% | — |
| GDPval | 42.5% | — |
| Remote Labor Index | 2.1% | — |
| τ²-bench Airline | 72% | — |
| τ²-bench Banking | 25.3% | — |
| τ²-bench Retail | 72.4% | — |
| τ²-bench Telecom | 84.9% | — |
| Cybench | 60% | — |
| DeepResearch Bench | 52.6% | — |
| OSWorld | 62.9% | — |
| LMArena Search | 1159 | — |
| METR Time Horizons | 67.4% | — |
| Vending-Bench 2 | 3,839 | — |

## Reasoning

- Claude Sonnet 4.5: 26.9 (#125)
- Step 3: 28.4 (#105)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| Kagi LLM Benchmark | 57.9% | 62.3% |
| LMArena Hard Prompts | 1462 | 1355 |
| ARC-AGI-2 | 13.6% | — |
| SimpleBench | 54.3% | — |
| NYT Connections (extended) | 37.3% | — |
| ARC-AGI-1 | 63.7% | — |
| CritPt | 1.1% | — |
| Chess Puzzles | 12% | — |
| EnigmaEval | 6% | — |
| EBR-Bench | 2.4% | — |
| Mystery Game Puzzles | 17% | — |
| DTBench | 83.2% | — |
| LMCA | 38.8% | — |
| Epoch Capabilities Index | 146.84 | — |
| ForecastBench | 61.9 | — |

## Math

- Claude Sonnet 4.5: 32.3 (#216)
- Step 3: 37.6 (#148)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Math | 1449 | 1366 |
| FrontierMath (Tiers 1-3) | 23.9% | — |
| FrontierMath Tier 4 | 2.4% | — |
| OTIS Mock AIME 2024-2025 | 77.8% | — |
| ProofBench | 19% | — |
| Omni-MATH | 55.3% | — |
| MATH Level 5 | 97.7% | — |
| FrontierMath (Feb 2025 set) | 15.2% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |

## Knowledge

- Claude Sonnet 4.5: 48.4 (#76)
- Step 3: 36.8 (#164)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Expert | 1482 | 1333 |
| GPQA Diamond | 82.3% | — |
| Humanity's Last Exam | 13.7% | — |
| SimpleQA Verified | 30.7% | — |
| MMLU-Pro | 86.9% | — |
| Vectara Hallucination Rate | 12% | — |
| GPQA (HELM) | 68.6% | — |

## Multimodal

- Claude Sonnet 4.5: 34.8 (#89)
- Step 3: 35.5 (#86)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Vision | — | 1177 |
| VPCT | 39.8% | — |
| LMArena Document | 1450 | — |

## Multilingual

- Claude Sonnet 4.5: 53.4 (#69)
- Step 3: 46.3 (#159)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Non-English | 1425 | 1327 |
| LMArena Chinese | 1459 | 1397 |
| LMArena German | 1427 | 1371 |
| LMArena Korean | 1403 | 1269 |
| LMArena Russian | 1437 | 1331 |
| LMArena Spanish | 1457 | 1371 |
| LMArena French | 1458 | — |
| LMArena Japanese | 1390 | — |

## Instruction Following

- Claude Sonnet 4.5: 75.0 (#78)
- Step 3: 70.4 (#164)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Instruction Following | 1459 | 1332 |
| IFEval | 85% | — |

## Long Context

- Claude Sonnet 4.5: 45.2 (#46)
- Step 3: 40.3 (#157)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Longer Query | 1476 | 1326 |

## Writing & Preference

- Claude Sonnet 4.5: 66.5 (#34)
- Step 3: 54.3 (#151)

| Benchmark | Claude Sonnet 4.5 | Step 3 |
|---|---|---|
| LMArena Text | 1439 | 1350 |
| LMArena Creative Writing | 1442 | 1321 |
| LMArena Multi-Turn | 1465 | 1341 |
| EQ-Bench Creative Writing | 1678 | — |
| WildBench | 85.4% | — |

## FAQ

### Is Claude Sonnet 4.5 better than Step 3?

Claude Sonnet 4.5 is the stronger model overall, scoring 44.1 to 40.5 on the Noometry Index.

### Is Claude Sonnet 4.5 or Step 3 better for coding?

Claude Sonnet 4.5 scores higher on coding benchmarks: 47.3 versus 40.1 in the Noometry coding category.

### How many benchmarks do Claude Sonnet 4.5 and Step 3 share?

16 benchmarks have published results for both models. Claude Sonnet 4.5 has 73 scored results on Noometry and Step 3 has 17.