# Step 3.5 Flash vs Step 5 Preview

> Step 5 Preview is the stronger model overall, scoring 47.9 to 42.3 on the Noometry Index. Step 3.5 Flash costs 9.5× less per token, which makes it the better buy when Step 5 Preview's lead doesn't matter for your workload.

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

## Summary

- They share 13 benchmarks with published results for both. Step 3.5 Flash scores higher in 0 categories and Step 5 Preview in 8 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Step 5 Preview leads 40.0 to 22.2.
- Step 3.5 Flash is cheaper at $0.10 / $0.30 per million input/output tokens, against $1 / $2.70 for Step 5 Preview.
- Step 5 Preview accepts more context: 1.02M tokens versus 256K.
- Step 3.5 Flash has downloadable open weights; the other is API-only.

## Snapshot

| | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| Provider | StepFun | StepFun |
| Noometry Index | 42.3 | 47.9 |
| Rank | 116 | 58 |
| Context | 256K | 1.02M |
| Input $/M | $0.10 | $1 |
| Output $/M | $0.30 | $2.70 |
| Weights | Open | Proprietary |

## Coding

- Step 3.5 Flash: 42.4 (#105)
- Step 5 Preview: 51.8 (#36)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Coding | 1436 | 1480 |
| LMArena WebDev | — | 1564 |
| SciCode | — | 58.9% |

## Reasoning

- Step 3.5 Flash: 22.2 (#202)
- Step 5 Preview: 40.0 (#57)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Hard Prompts | 1411 | 1465 |
| NYT Connections (extended) | 28.4% | — |
| CritPt | — | 20.9% |

## Math

- Step 3.5 Flash: 42.6 (#84)
- Step 5 Preview: 46.1 (#72)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Math | 1408 | 1470 |
| MathArena Final-Answer Competitions | 66.8% | — |
| ProofBench | — | 42% |

## Knowledge

- Step 3.5 Flash: 39.6 (#132)
- Step 5 Preview: 41.2 (#112)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Expert | 1421 | 1470 |

## Multimodal

- Step 3.5 Flash: —
- Step 5 Preview: 41.0 (#41)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Vision | — | 1267 |

## Multilingual

- Step 3.5 Flash: 50.5 (#119)
- Step 5 Preview: 53.8 (#54)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Non-English | 1385 | 1432 |
| LMArena Chinese | 1447 | 1519 |
| LMArena Russian | 1385 | 1436 |
| LMArena Spanish | 1419 | 1439 |
| LMArena French | 1421 | — |
| LMArena German | 1405 | — |
| LMArena Japanese | 1354 | — |
| LMArena Korean | 1352 | — |

## Instruction Following

- Step 3.5 Flash: 73.1 (#124)
- Step 5 Preview: 76.0 (#50)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Instruction Following | 1385 | 1444 |

## Long Context

- Step 3.5 Flash: 42.8 (#117)
- Step 5 Preview: 44.5 (#64)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Longer Query | 1402 | 1455 |

## Writing & Preference

- Step 3.5 Flash: 58.8 (#113)
- Step 5 Preview: 62.8 (#71)

| Benchmark | Step 3.5 Flash | Step 5 Preview |
|---|---|---|
| LMArena Text | 1403 | 1442 |
| LMArena Creative Writing | 1357 | 1410 |
| LMArena Multi-Turn | 1405 | 1447 |

## FAQ

### Is Step 3.5 Flash better than Step 5 Preview?

Step 5 Preview is the stronger model overall, scoring 47.9 to 42.3 on the Noometry Index. Step 3.5 Flash costs 9.5× less per token, which makes it the better buy when Step 5 Preview's lead doesn't matter for your workload.

### Which is cheaper, Step 3.5 Flash or Step 5 Preview?

Step 3.5 Flash is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; Step 5 Preview lists at $1 and $2.70.

### Is Step 3.5 Flash or Step 5 Preview better for coding?

Step 5 Preview scores higher on coding benchmarks: 51.8 versus 42.4 in the Noometry coding category.

### Which has the bigger context window?

Step 5 Preview does, with 1.02M tokens against 256K.

### How many benchmarks do Step 3.5 Flash and Step 5 Preview share?

13 benchmarks have published results for both models. Step 3.5 Flash has 19 scored results on Noometry and Step 5 Preview has 18.