# Claude 3 Sonnet vs Step 3.5 Flash

> Step 3.5 Flash is the stronger model overall, scoring 42.3 to 29.0 on the Noometry Index.

- Canonical page: https://noometry.com/compare/claude-3-sonnet-vs-step-3-5-flash
- Last updated: 2026-10-11
- Shared benchmarks: 17

## Summary

- They share 17 benchmarks with published results for both. Claude 3 Sonnet scores higher in 0 categories and Step 3.5 Flash in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in math, where Step 3.5 Flash leads 42.6 to 10.7.
- Step 3.5 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| Provider | Anthropic | StepFun |
| Noometry Index | 29.0 | 42.3 |
| Rank | 319 | 116 |
| Context | — | 256K |
| Input $/M | — | $0.10 |
| Output $/M | — | $0.30 |
| Weights | Proprietary | Open |

## Coding

- Claude 3 Sonnet: 29.6 (#302)
- Step 3.5 Flash: 42.4 (#105)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1223 | 1436 |
| WeirdML | 10.2% | — |
| BigCodeBench Instruct | 42.7% | — |
| BigCodeBench Complete | 53.8% | — |
| HumanEval+ | 64% | — |
| MBPP+ | 69.3% | — |

## Reasoning

- Claude 3 Sonnet: 20.5 (#237)
- Step 3.5 Flash: 22.2 (#202)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Hard Prompts | 1197 | 1411 |
| NYT Connections (extended) | — | 28.4% |
| DTBench | 53.6% | — |
| Epoch Capabilities Index | 120.7 | — |
| WinoGrande | 75.1% | — |

## Math

- Claude 3 Sonnet: 10.7 (#310)
- Step 3.5 Flash: 42.6 (#84)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Math | 1213 | 1408 |
| MathArena Final-Answer Competitions | — | 66.8% |
| OTIS Mock AIME 2024-2025 | 2.5% | — |
| MATH Level 5 | 18.2% | — |

## Knowledge

- Claude 3 Sonnet: 21.1 (#276)
- Step 3.5 Flash: 39.6 (#132)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | 1173 | 1421 |
| GPQA Diamond | 40.6% | — |
| MMLU | 75.9% | — |

## Multimodal

- Claude 3 Sonnet: 25.2 (#125)
- Step 3.5 Flash: —

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Vision | 984 | — |

## Multilingual

- Claude 3 Sonnet: 37.8 (#234)
- Step 3.5 Flash: 50.5 (#119)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1205 | 1385 |
| LMArena Chinese | 1189 | 1447 |
| LMArena French | 1229 | 1421 |
| LMArena German | 1204 | 1405 |
| LMArena Japanese | 1131 | 1354 |
| LMArena Korean | 1128 | 1352 |
| LMArena Russian | 1227 | 1385 |
| LMArena Spanish | 1204 | 1419 |

## Instruction Following

- Claude 3 Sonnet: 62.8 (#235)
- Step 3.5 Flash: 73.1 (#124)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1199 | 1385 |

## Long Context

- Claude 3 Sonnet: 36.7 (#228)
- Step 3.5 Flash: 42.8 (#117)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1211 | 1402 |

## Writing & Preference

- Claude 3 Sonnet: 42.1 (#238)
- Step 3.5 Flash: 58.8 (#113)

| Benchmark | Claude 3 Sonnet | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1218 | 1403 |
| LMArena Creative Writing | 1186 | 1357 |
| LMArena Multi-Turn | 1227 | 1405 |

## FAQ

### Is Claude 3 Sonnet better than Step 3.5 Flash?

Step 3.5 Flash is the stronger model overall, scoring 42.3 to 29.0 on the Noometry Index.

### Is Claude 3 Sonnet or Step 3.5 Flash better for coding?

Step 3.5 Flash scores higher on coding benchmarks: 42.4 versus 29.6 in the Noometry coding category.

### How many benchmarks do Claude 3 Sonnet and Step 3.5 Flash share?

17 benchmarks have published results for both models. Claude 3 Sonnet has 30 scored results on Noometry and Step 3.5 Flash has 19.