# Grok 4.1 Fast vs Step 5 Preview

> Step 5 Preview is the stronger model overall, scoring 47.9 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 5.2× 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/grok-4-1-fast-vs-step-5-preview
- Last updated: 2026-10-11
- Shared benchmarks: 16

## Summary

- They share 16 benchmarks with published results for both. Grok 4.1 Fast scores higher in 1 category and Step 5 Preview in 8 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in coding, where Step 5 Preview leads 51.8 to 34.1.
- The biggest single-benchmark swing is ProofBench: 4% for Grok 4.1 Fast and 42% for Step 5 Preview.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $1 / $2.70 for Step 5 Preview.
- Step 5 Preview accepts more context: 1.02M tokens versus 128K.

## Snapshot

| | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| Provider | xAI | StepFun |
| Noometry Index | 41.4 | 47.9 |
| Rank | 136 | 58 |
| Context | 128K | 1.02M |
| Input $/M | $0.20 | $1 |
| Output $/M | $0.50 | $2.70 |
| Weights | Proprietary | Proprietary |

## Coding

- Grok 4.1 Fast: 34.1 (#245)
- Step 5 Preview: 51.8 (#36)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena WebDev | 1242 | 1564 |
| LMArena Coding | 1411 | 1480 |
| SciCode | — | 58.9% |
| ALE-Bench | 394.93 | — |

## Agentic & Tool Use

- Grok 4.1 Fast: 36.3 (#39)
- Step 5 Preview: —

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| Berkeley Function Calling Leaderboard | 69.6% | — |
| τ²-bench Banking | 13.1% | — |
| LMArena Search | 1171 | — |
| Vending-Bench 2 | 1,107 | — |

## Reasoning

- Grok 4.1 Fast: 43.4 (#49)
- Step 5 Preview: 40.0 (#57)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena Hard Prompts | 1407 | 1465 |
| SimpleBench | 56% | — |
| NYT Connections (extended) | 87.4% | — |
| CritPt | — | 20.9% |
| DTBench | 87.7% | — |
| ForecastBench | 61 | — |

## Math

- Grok 4.1 Fast: 31.9 (#221)
- Step 5 Preview: 46.1 (#72)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| ProofBench | 4% | 42% |
| LMArena Math | 1408 | 1470 |
| MathArena Final-Answer Competitions | 60.9% | — |

## Knowledge

- Grok 4.1 Fast: 33.1 (#207)
- Step 5 Preview: 41.2 (#112)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena Expert | 1399 | 1470 |
| Vectara Hallucination Rate | 17.8% | — |

## Multimodal

- Grok 4.1 Fast: 37.0 (#76)
- Step 5 Preview: 41.0 (#41)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena Vision | 1201 | 1267 |

## Multilingual

- Grok 4.1 Fast: 51.0 (#114)
- Step 5 Preview: 53.8 (#54)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena Non-English | 1391 | 1432 |
| LMArena Chinese | 1441 | 1519 |
| LMArena Russian | 1387 | 1436 |
| LMArena Spanish | 1413 | 1439 |
| LMArena French | 1415 | — |
| LMArena German | 1404 | — |
| LMArena Japanese | 1349 | — |
| LMArena Korean | 1361 | — |

## Instruction Following

- Grok 4.1 Fast: 72.7 (#133)
- Step 5 Preview: 76.0 (#50)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena Instruction Following | 1376 | 1444 |

## Long Context

- Grok 4.1 Fast: 42.4 (#126)
- Step 5 Preview: 44.5 (#64)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena Longer Query | 1390 | 1455 |

## Writing & Preference

- Grok 4.1 Fast: 57.2 (#131)
- Step 5 Preview: 62.8 (#71)

| Benchmark | Grok 4.1 Fast | Step 5 Preview |
|---|---|---|
| LMArena Text | 1408 | 1442 |
| LMArena Creative Writing | 1394 | 1410 |
| LMArena Multi-Turn | 1389 | 1447 |
| EQ-Bench Creative Writing | 1327 | — |

## FAQ

### Is Grok 4.1 Fast better than Step 5 Preview?

Step 5 Preview is the stronger model overall, scoring 47.9 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 5.2× less per token, which makes it the better buy when Step 5 Preview's lead doesn't matter for your workload.

### Which is cheaper, Grok 4.1 Fast or Step 5 Preview?

Grok 4.1 Fast is cheaper. It lists at $0.20 per million input tokens and $0.50 per million output tokens; Step 5 Preview lists at $1 and $2.70.

### Is Grok 4.1 Fast or Step 5 Preview better for coding?

Step 5 Preview scores higher on coding benchmarks: 51.8 versus 34.1 in the Noometry coding category.

### Which has the bigger context window?

Step 5 Preview does, with 1.02M tokens against 128K.

### How many benchmarks do Grok 4.1 Fast and Step 5 Preview share?

16 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and Step 5 Preview has 18.