# Grok 4.1 Fast vs Phi 3 Small 8k Instruct

> Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 28.8 on the Noometry Index.

- Canonical page: https://noometry.com/compare/grok-4-1-fast-vs-phi-3-small-8k-instruct
- Last updated: 2026-10-10
- Shared benchmarks: 17

## Summary

- They share 17 benchmarks with published results for both. Grok 4.1 Fast scores higher in 8 categories and Phi 3 Small 8k Instruct in 0 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Grok 4.1 Fast leads 42.3 to 14.2.
- Phi 3 Small 8k Instruct has downloadable open weights; the other is API-only.

## Snapshot

| | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| Provider | xAI | Microsoft |
| Noometry Index | 40.9 | 28.8 |
| Rank | 131 | 310 |
| Context | 128K | — |
| Input $/M | $0.20 | — |
| Output $/M | $0.50 | — |
| Weights | Proprietary | Open |

## Coding

- Grok 4.1 Fast: 33.8 (#236)
- Phi 3 Small 8k Instruct: 27.4 (#313)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Coding | 1411 | 1102 |
| LMArena WebDev | 1241 | — |
| LiveBench Coding | — | 20.3% |
| ALE-Bench | 394.93 | — |

## Agentic & Tool Use

- Grok 4.1 Fast: 36.1 (#35)
- Phi 3 Small 8k Instruct: —

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| Berkeley Function Calling Leaderboard | 69.6% | — |
| τ²-bench Banking | 13.1% | — |
| LMArena Search | 1171 | — |
| Vending-Bench 2 | 1,107 | — |

## Reasoning

- Grok 4.1 Fast: 42.3 (#45)
- Phi 3 Small 8k Instruct: 14.2 (#319)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Hard Prompts | 1407 | 1100 |
| SimpleBench | 56% | — |
| NYT Connections (extended) | 87.4% | — |
| LiveBench Reasoning | — | 15.9% |
| DTBench | 87.7% | — |
| LiveBench Data Analysis | — | 30.3% |
| Adversarial NLI | — | 58.1% |
| BIG-Bench Hard | — | 79.1% |
| ForecastBench | 61 | — |
| HellaSwag | — | 77% |
| LiveBench | — | 24% |
| WinoGrande | — | 81.5% |

## Math

- Grok 4.1 Fast: 30.9 (#201)
- Phi 3 Small 8k Instruct: 25.4 (#247)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Math | 1408 | 1151 |
| MathArena Final-Answer Competitions | 60.9% | — |
| ProofBench | 4% | — |
| LiveBench Math | — | 17.6% |

## Knowledge

- Grok 4.1 Fast: 32.6 (#203)
- Phi 3 Small 8k Instruct: 28.5 (#237)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Expert | 1398 | 1067 |
| Vectara Hallucination Rate | 17.8% | — |
| ARC (AI2) Challenge | — | 90.7% |
| MMLU | — | 75.7% |
| OpenBookQA | — | 88% |
| TriviaQA | — | 58.1% |

## Multimodal

- Grok 4.1 Fast: 36.3 (#71)
- Phi 3 Small 8k Instruct: —

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Vision | 1201 | — |

## Multilingual

- Grok 4.1 Fast: 51.1 (#110)
- Phi 3 Small 8k Instruct: 28.6 (#267)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Non-English | 1391 | 1058 |
| LMArena Chinese | 1441 | 1061 |
| LMArena French | 1416 | 1134 |
| LMArena German | 1404 | 1080 |
| LMArena Japanese | 1347 | 966 |
| LMArena Korean | 1361 | 894 |
| LMArena Russian | 1387 | 1111 |
| LMArena Spanish | 1411 | 1111 |

## Instruction Following

- Grok 4.1 Fast: 72.8 (#127)
- Phi 3 Small 8k Instruct: 52.2 (#287)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Instruction Following | 1376 | 1087 |
| LiveBench Instruction Following | — | 47.2% |

## Long Context

- Grok 4.1 Fast: 42.4 (#121)
- Phi 3 Small 8k Instruct: 33.0 (#262)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Longer Query | 1390 | 1088 |

## Writing & Preference

- Grok 4.1 Fast: 57.4 (#126)
- Phi 3 Small 8k Instruct: 31.3 (#279)

| Benchmark | Grok 4.1 Fast | Phi 3 Small 8k Instruct |
|---|---|---|
| LMArena Text | 1408 | 1110 |
| LMArena Creative Writing | 1394 | 1083 |
| LMArena Multi-Turn | 1389 | 1068 |
| EQ-Bench Creative Writing | 1327 | — |
| LiveBench Language | — | 12.9% |

## FAQ

### Is Grok 4.1 Fast better than Phi 3 Small 8k Instruct?

Grok 4.1 Fast is the stronger model overall, scoring 40.9 to 28.8 on the Noometry Index.

### Is Grok 4.1 Fast or Phi 3 Small 8k Instruct better for coding?

Grok 4.1 Fast scores higher on coding benchmarks: 33.8 versus 27.4 in the Noometry coding category.

### How many benchmarks do Grok 4.1 Fast and Phi 3 Small 8k Instruct share?

17 benchmarks have published results for both models. Grok 4.1 Fast has 32 scored results on Noometry and Phi 3 Small 8k Instruct has 32.