# Grok 4 Fast vs Qwen3.5-Flash

> Qwen3.5-Flash is the stronger model overall, scoring 42.3 to 39.0 on the Noometry Index.

- Canonical page: https://noometry.com/compare/grok-4-fast-vs-qwen3-5-flash
- Last updated: 2026-10-10
- Shared benchmarks: 21

## Summary

- They share 21 benchmarks with published results for both. Grok 4 Fast scores higher in 4 categories and Qwen3.5-Flash in 4 categories; 5 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 Vectara Hallucination Rate: 19.7% for Grok 4 Fast and 10.5% for Qwen3.5-Flash.

## Snapshot

| | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| Provider | xAI | Alibaba (Qwen) |
| Noometry Index | 39.0 | 42.3 |
| Rank | 164 | 105 |
| Context | — | 1M |
| Input $/M | — | $0.10 |
| Output $/M | — | $0.40 |
| Weights | Proprietary | Proprietary |

## Coding

- Grok 4 Fast: 32.3 (#264)
- Qwen3.5-Flash: 33.9 (#234)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| LMArena WebDev | 1160 | 1243 |
| LMArena Coding | 1429 | 1412 |
| WeirdML | 42.9% | — |
| ALE-Bench | — | 221.8 |

## Agentic & Tool Use

- Grok 4 Fast: 29.3 (#80)
- Qwen3.5-Flash: —

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |
| Vending-Bench 2 | — | 462.69 |

## Reasoning

- Grok 4 Fast: 22.5 (#179)
- Qwen3.5-Flash: 32.9 (#63)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| LMArena Hard Prompts | 1413 | 1404 |
| DTBench | 82.7% | 82.9% |
| Epoch Capabilities Index | 144.21 | 143.98 |
| ARC-AGI-2 | 5.3% | — |
| Kagi LLM Benchmark | 66.1% | — |
| ARC-AGI-1 | 48.5% | — |
| Chess Puzzles | — | 21% |
| Mystery Game Puzzles | — | 20% |
| LMCA | — | 29.1% |
| ForecastBench | 60.5 | — |

## Math

- Grok 4 Fast: 36.1 (#126)
- Qwen3.5-Flash: 36.3 (#117)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| LMArena Math | 1419 | 1407 |
| FrontierMath (Tiers 1-3) | — | 18.2% |
| OTIS Mock AIME 2024-2025 | — | 84.4% |
| FrontierMath (Feb 2025 set) | — | 6.2% |
| FrontierMath Tier 4 (v1) | — | 0% |

## Knowledge

- Grok 4 Fast: 31.5 (#211)
- Qwen3.5-Flash: 43.2 (#84)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| Vectara Hallucination Rate | 19.7% | 10.5% |
| LMArena Expert | 1411 | 1408 |
| GPQA Diamond | — | 82.3% |
| SimpleQA Verified | — | 20.3% |

## Multilingual

- Grok 4 Fast: 51.5 (#106)
- Qwen3.5-Flash: 50.7 (#116)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| LMArena Non-English | 1397 | 1385 |
| LMArena Chinese | 1458 | 1446 |
| LMArena French | 1433 | 1412 |
| LMArena German | 1383 | 1389 |
| LMArena Japanese | 1358 | 1369 |
| LMArena Korean | 1359 | 1344 |
| LMArena Russian | 1387 | 1379 |
| LMArena Spanish | 1414 | 1399 |

## Instruction Following

- Grok 4 Fast: 73.4 (#116)
- Qwen3.5-Flash: 72.8 (#133)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| LMArena Instruction Following | 1388 | 1374 |

## Long Context

- Grok 4 Fast: 63.2 (#3)
- Qwen3.5-Flash: 42.4 (#119)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| LMArena Longer Query | 1415 | 1392 |
| Fiction.LiveBench | 94.4% | — |

## Writing & Preference

- Grok 4 Fast: 60.2 (#96)
- Qwen3.5-Flash: 58.2 (#117)

| Benchmark | Grok 4 Fast | Qwen3.5-Flash |
|---|---|---|
| LMArena Text | 1407 | 1397 |
| LMArena Creative Writing | 1388 | 1343 |
| LMArena Multi-Turn | 1414 | 1393 |

## FAQ

### Is Grok 4 Fast better than Qwen3.5-Flash?

Qwen3.5-Flash is the stronger model overall, scoring 42.3 to 39.0 on the Noometry Index.

### Is Grok 4 Fast or Qwen3.5-Flash better for coding?

Qwen3.5-Flash scores higher on coding benchmarks: 33.9 versus 32.3 in the Noometry coding category.

### How many benchmarks do Grok 4 Fast and Qwen3.5-Flash share?

21 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Qwen3.5-Flash has 32.