# Grok 4 Fast vs Phi-3.5-mini

> Grok 4 Fast has enough public results to be ranked (#167); Phi-3.5-mini does not yet, so treat this comparison as directional.

- Canonical page: https://noometry.com/compare/grok-4-fast-vs-phi-3-5-mini
- Last updated: 2026-10-11
- Shared benchmarks: 0

## Summary

- Phi-3.5-mini has downloadable open weights; the other is API-only.

## Snapshot

| | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| Provider | xAI | Microsoft |
| Noometry Index | 39.4 | 36.9 |
| Rank | 167 | — |
| Context | — | — |
| Input $/M | — | — |
| Output $/M | — | — |
| Weights | Proprietary | Open |

## Coding

- Grok 4 Fast: 32.5 (#271)
- Phi-3.5-mini: 34.6 (#232)

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| LMArena WebDev | 1159 | — |
| WeirdML | 42.9% | — |
| BigCodeBench Instruct | — | 32.8% |
| LMArena Coding | 1429 | — |
| BigCodeBench Complete | — | 38.5% |

## Agentic & Tool Use

- Grok 4 Fast: 29.5 (#86)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |

## Reasoning

- Grok 4 Fast: 22.2 (#201)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| ARC-AGI-2 | 5.3% | — |
| Kagi LLM Benchmark | 66.1% | — |
| ARC-AGI-1 | 48.5% | — |
| LMArena Hard Prompts | 1412 | — |
| DTBench | 82.7% | — |
| Epoch Capabilities Index | 144.2 | — |
| ForecastBench | 60.5 | — |
| PIQA | — | 81% |

## Math

- Grok 4 Fast: 38.9 (#123)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| LMArena Math | 1419 | — |
| GSM8K | — | 86.2% |

## Knowledge

- Grok 4 Fast: 32.0 (#214)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| Vectara Hallucination Rate | 19.7% | — |
| LMArena Expert | 1411 | — |
| BoolQ | — | 78% |

## Multilingual

- Grok 4 Fast: 51.3 (#111)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| LMArena Non-English | 1396 | — |
| LMArena Chinese | 1457 | — |
| LMArena French | 1431 | — |
| LMArena German | 1383 | — |
| LMArena Japanese | 1352 | — |
| LMArena Korean | 1357 | — |
| LMArena Russian | 1389 | — |
| LMArena Spanish | 1415 | — |

## Instruction Following

- Grok 4 Fast: 73.2 (#121)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| LMArena Instruction Following | 1387 | — |

## Long Context

- Grok 4 Fast: 63.2 (#3)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| Fiction.LiveBench | 94.4% | — |
| LMArena Longer Query | 1415 | — |

## Writing & Preference

- Grok 4 Fast: 60.0 (#102)
- Phi-3.5-mini: —

| Benchmark | Grok 4 Fast | Phi-3.5-mini |
|---|---|---|
| LMArena Text | 1407 | — |
| LMArena Creative Writing | 1387 | — |
| LMArena Multi-Turn | 1414 | — |

## FAQ

### Is Grok 4 Fast better than Phi-3.5-mini?

Grok 4 Fast has enough public results to be ranked (#167); Phi-3.5-mini does not yet, so treat this comparison as directional.

### Is Grok 4 Fast or Phi-3.5-mini better for coding?

Phi-3.5-mini scores higher on coding benchmarks: 34.6 versus 32.5 in the Noometry coding category.

### How many benchmarks do Grok 4 Fast and Phi-3.5-mini share?

0 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Phi-3.5-mini has 5.