# Grok 4.1 Fast vs Grok 4 Fast

> Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 39.0 on the Noometry Index.

- Canonical page: https://noometry.com/compare/grok-4-1-fast-vs-grok-4-fast
- Last updated: 2026-10-10
- Shared benchmarks: 23

## Summary

- They share 23 benchmarks with published results for both. Grok 4.1 Fast scores higher in 4 categories and Grok 4 Fast in 5 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 42.4.
- The biggest single-benchmark swing is DTBench: 87.7% for Grok 4.1 Fast and 82.7% for Grok 4 Fast.

## Snapshot

| | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| Provider | xAI | xAI |
| Noometry Index | 40.9 | 39.0 |
| Rank | 131 | 164 |
| Context | 128K | — |
| Input $/M | $0.20 | — |
| Output $/M | $0.50 | — |
| Weights | Proprietary | Proprietary |

## Coding

- Grok 4.1 Fast: 33.8 (#236)
- Grok 4 Fast: 32.3 (#264)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena WebDev | 1241 | 1160 |
| LMArena Coding | 1411 | 1429 |
| WeirdML | — | 42.9% |
| ALE-Bench | 394.93 | — |

## Agentic & Tool Use

- Grok 4.1 Fast: 36.1 (#35)
- Grok 4 Fast: 29.3 (#80)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| τ²-bench Banking | 13.1% | 15.7% |
| LMArena Search | 1171 | 1171 |
| Berkeley Function Calling Leaderboard | 69.6% | — |
| Cybench | — | 30% |
| Vending-Bench 2 | 1,107 | — |

## Reasoning

- Grok 4.1 Fast: 42.3 (#45)
- Grok 4 Fast: 22.5 (#179)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena Hard Prompts | 1407 | 1413 |
| DTBench | 87.7% | 82.7% |
| ForecastBench | 61 | 60.5 |
| ARC-AGI-2 | — | 5.3% |
| SimpleBench | 56% | — |
| Kagi LLM Benchmark | — | 66.1% |
| NYT Connections (extended) | 87.4% | — |
| ARC-AGI-1 | — | 48.5% |
| Epoch Capabilities Index | — | 144.21 |

## Math

- Grok 4.1 Fast: 30.9 (#201)
- Grok 4 Fast: 36.1 (#126)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena Math | 1408 | 1419 |
| MathArena Final-Answer Competitions | 60.9% | — |
| ProofBench | 4% | — |

## Knowledge

- Grok 4.1 Fast: 32.6 (#203)
- Grok 4 Fast: 31.5 (#211)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| Vectara Hallucination Rate | 17.8% | 19.7% |
| LMArena Expert | 1398 | 1411 |

## Multimodal

- Grok 4.1 Fast: 36.3 (#71)
- Grok 4 Fast: —

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena Vision | 1201 | — |

## Multilingual

- Grok 4.1 Fast: 51.1 (#110)
- Grok 4 Fast: 51.5 (#106)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena Non-English | 1391 | 1397 |
| LMArena Chinese | 1441 | 1458 |
| LMArena French | 1416 | 1433 |
| LMArena German | 1404 | 1383 |
| LMArena Japanese | 1347 | 1358 |
| LMArena Korean | 1361 | 1359 |
| LMArena Russian | 1387 | 1387 |
| LMArena Spanish | 1411 | 1414 |

## Instruction Following

- Grok 4.1 Fast: 72.8 (#127)
- Grok 4 Fast: 73.4 (#116)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena Instruction Following | 1376 | 1388 |

## Long Context

- Grok 4.1 Fast: 42.4 (#121)
- Grok 4 Fast: 63.2 (#3)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena Longer Query | 1390 | 1415 |
| Fiction.LiveBench | — | 94.4% |

## Writing & Preference

- Grok 4.1 Fast: 57.4 (#126)
- Grok 4 Fast: 60.2 (#96)

| Benchmark | Grok 4.1 Fast | Grok 4 Fast |
|---|---|---|
| LMArena Text | 1408 | 1407 |
| LMArena Creative Writing | 1394 | 1388 |
| LMArena Multi-Turn | 1389 | 1414 |
| EQ-Bench Creative Writing | 1327 | — |

## FAQ

### Is Grok 4.1 Fast better than Grok 4 Fast?

Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 39.0 on the Noometry Index.

### Is Grok 4.1 Fast or Grok 4 Fast better for coding?

Grok 4.1 Fast scores higher on coding benchmarks: 33.8 versus 32.3 in the Noometry coding category.

### How many benchmarks do Grok 4.1 Fast and Grok 4 Fast share?

23 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and Grok 4 Fast has 30.