# Grok 4 Fast vs Phi 3 Mini 128k Instruct

> Grok 4 Fast is the stronger model overall, scoring 39.4 to 29.7 on the Noometry Index.

- Canonical page: https://noometry.com/compare/grok-4-fast-vs-phi-3-mini-128k-instruct
- Last updated: 2026-10-11
- Shared benchmarks: 17

## Summary

- They share 17 benchmarks with published results for both. Grok 4 Fast scores higher in 8 categories and Phi 3 Mini 128k Instruct in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 30.4.
- Phi 3 Mini 128k Instruct has downloadable open weights; the other is API-only.

## Snapshot

| | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| Provider | xAI | Microsoft |
| Noometry Index | 39.4 | 29.7 |
| Rank | 167 | 305 |
| Context | — | — |
| Input $/M | — | — |
| Output $/M | — | — |
| Weights | Proprietary | Open |

## Coding

- Grok 4 Fast: 32.5 (#271)
- Phi 3 Mini 128k Instruct: 28.8 (#312)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Coding | 1429 | 1039 |
| LMArena WebDev | 1159 | — |
| WeirdML | 42.9% | — |
| BigCodeBench Instruct | — | 29.6% |
| BigCodeBench Complete | — | 40.6% |

## Agentic & Tool Use

- Grok 4 Fast: 29.5 (#86)
- Phi 3 Mini 128k Instruct: —

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| τ²-bench Banking | 15.7% | — |
| Cybench | 30% | — |
| LMArena Search | 1171 | — |

## Reasoning

- Grok 4 Fast: 22.2 (#201)
- Phi 3 Mini 128k Instruct: 19.6 (#256)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Hard Prompts | 1412 | 1028 |
| ARC-AGI-2 | 5.3% | — |
| Kagi LLM Benchmark | 66.1% | — |
| ARC-AGI-1 | 48.5% | — |
| DTBench | 82.7% | — |
| Epoch Capabilities Index | 144.2 | — |
| ForecastBench | 60.5 | — |

## Math

- Grok 4 Fast: 38.9 (#123)
- Phi 3 Mini 128k Instruct: 31.6 (#222)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Math | 1419 | 1089 |

## Knowledge

- Grok 4 Fast: 32.0 (#214)
- Phi 3 Mini 128k Instruct: 26.8 (#254)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Expert | 1411 | 984 |
| Vectara Hallucination Rate | 19.7% | — |

## Multilingual

- Grok 4 Fast: 51.3 (#111)
- Phi 3 Mini 128k Instruct: 25.2 (#285)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Non-English | 1396 | 1000 |
| LMArena Chinese | 1457 | 1016 |
| LMArena French | 1431 | 1039 |
| LMArena German | 1383 | 1006 |
| LMArena Japanese | 1352 | 899 |
| LMArena Korean | 1357 | 856 |
| LMArena Russian | 1389 | 1004 |
| LMArena Spanish | 1415 | 1059 |

## Instruction Following

- Grok 4 Fast: 73.2 (#121)
- Phi 3 Mini 128k Instruct: 51.8 (#294)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Instruction Following | 1387 | 1023 |

## Long Context

- Grok 4 Fast: 63.2 (#3)
- Phi 3 Mini 128k Instruct: 30.4 (#289)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Longer Query | 1415 | 996 |
| Fiction.LiveBench | 94.4% | — |

## Writing & Preference

- Grok 4 Fast: 60.0 (#102)
- Phi 3 Mini 128k Instruct: 27.1 (#301)

| Benchmark | Grok 4 Fast | Phi 3 Mini 128k Instruct |
|---|---|---|
| LMArena Text | 1407 | 1050 |
| LMArena Creative Writing | 1387 | 1024 |
| LMArena Multi-Turn | 1414 | 989 |

## FAQ

### Is Grok 4 Fast better than Phi 3 Mini 128k Instruct?

Grok 4 Fast is the stronger model overall, scoring 39.4 to 29.7 on the Noometry Index.

### Is Grok 4 Fast or Phi 3 Mini 128k Instruct better for coding?

Grok 4 Fast scores higher on coding benchmarks: 32.5 versus 28.8 in the Noometry coding category.

### How many benchmarks do Grok 4 Fast and Phi 3 Mini 128k Instruct share?

17 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Phi 3 Mini 128k Instruct has 19.