# Grok 4 Fast vs Kimi K3

> Kimi K3 is the stronger model overall, scoring 59.5 to 39.4 on the Noometry Index.

- Canonical page: https://noometry.com/compare/grok-4-fast-vs-kimi-k3
- Last updated: 2026-10-10
- Shared benchmarks: 25

## Summary

- They share 25 benchmarks with published results for both. Grok 4 Fast scores higher in 1 category and Kimi K3 in 8 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Kimi K3 leads 63.0 to 22.2.
- The biggest single-benchmark swing is ARC-AGI-2: 5.3% for Grok 4 Fast and 60.4% for Kimi K3.
- Kimi K3 has downloadable open weights; the other is API-only.

## Snapshot

| | Grok 4 Fast | Kimi K3 |
|---|---|---|
| Provider | xAI | Moonshot AI |
| Noometry Index | 39.4 | 59.5 |
| Rank | 167 | 15 |
| Context | — | 1.05M |
| Input $/M | — | $3 |
| Output $/M | — | $15 |
| Weights | Proprietary | Open |

## Coding

- Grok 4 Fast: 32.5 (#271)
- Kimi K3: 61.0 (#10)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| LMArena WebDev | 1159 | 1654 |
| WeirdML | 42.9% | 82.6% |
| LMArena Coding | 1429 | 1508 |
| DeepSWE | — | 68.5% |
| FrontierCode | — | 44.2% |
| FrontierSWE | — | 25.9% |
| SciCode | — | 59.5% |
| ALE-Bench | — | 1,524 |

## Agentic & Tool Use

- Grok 4 Fast: 29.5 (#86)
- Kimi K3: 41.8 (#20)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| τ²-bench Banking | 15.7% | 37.1% |
| APEX-Agents | — | 50.6% |
| Cybench | 30% | — |
| PostTrainBench | — | 32% |
| GBAEval | — | 48.3% |
| GDP.pdf | — | 19% |
| LMArena Search | 1171 | — |
| Vending-Bench 2 | — | 5,165 |

## Reasoning

- Grok 4 Fast: 22.2 (#201)
- Kimi K3: 63.0 (#17)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| ARC-AGI-2 | 5.3% | 60.4% |
| ARC-AGI-1 | 48.5% | 94.5% |
| LMArena Hard Prompts | 1412 | 1496 |
| DTBench | 82.7% | 91.2% |
| Epoch Capabilities Index | 144.2 | 157.45 |
| ForecastBench | 60.5 | 61.1 |
| SimpleBench | — | 60.7% |
| Kagi LLM Benchmark | 66.1% | — |
| NYT Connections (extended) | — | 93.6% |
| CritPt | — | 23.4% |
| Chess Puzzles | — | 39% |
| Mystery Game Puzzles | — | 26% |
| LMCA | — | 52.7% |
| Surface Evolver Bench | — | 95% |

## Math

- Grok 4 Fast: 38.9 (#123)
- Kimi K3: 74.2 (#16)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| LMArena Math | 1419 | 1491 |
| FrontierMath (Tiers 1-3) | — | 72.2% |
| FrontierMath Tier 4 | — | 39% |
| MathArena Final-Answer Competitions | — | 87.8% |
| OTIS Mock AIME 2024-2025 | — | 97.2% |
| ProofBench | — | 87% |

## Knowledge

- Grok 4 Fast: 32.0 (#214)
- Kimi K3: 63.2 (#21)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| LMArena Expert | 1411 | 1521 |
| GPQA Diamond | — | 93.1% |
| SimpleQA Verified | — | 50.6% |
| Vectara Hallucination Rate | 19.7% | — |

## Multimodal

- Grok 4 Fast: —
- Kimi K3: 37.8 (#70)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| Blueprint-Bench 2 | — | 29.5% |
| Furniture Assembly | — | 34.2% |

## Multilingual

- Grok 4 Fast: 51.3 (#111)
- Kimi K3: 56.3 (#21)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| LMArena Non-English | 1396 | 1466 |
| LMArena Chinese | 1457 | 1529 |
| LMArena French | 1431 | 1491 |
| LMArena German | 1383 | 1488 |
| LMArena Japanese | 1352 | 1487 |
| LMArena Korean | 1357 | 1458 |
| LMArena Russian | 1389 | 1482 |
| LMArena Spanish | 1415 | 1472 |

## Instruction Following

- Grok 4 Fast: 73.2 (#121)
- Kimi K3: 77.7 (#14)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| LMArena Instruction Following | 1387 | 1483 |

## Long Context

- Grok 4 Fast: 63.2 (#3)
- Kimi K3: 45.8 (#29)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| LMArena Longer Query | 1415 | 1494 |
| Fiction.LiveBench | 94.4% | — |

## Writing & Preference

- Grok 4 Fast: 60.0 (#102)
- Kimi K3: 76.6 (#4)

| Benchmark | Grok 4 Fast | Kimi K3 |
|---|---|---|
| LMArena Text | 1407 | 1476 |
| LMArena Creative Writing | 1387 | 1454 |
| LMArena Multi-Turn | 1414 | 1488 |
| EQ-Bench Creative Writing | — | 2082 |
| EQ-Bench 4 | — | 1339 |

## FAQ

### Is Grok 4 Fast better than Kimi K3?

Kimi K3 is the stronger model overall, scoring 59.5 to 39.4 on the Noometry Index.

### Is Grok 4 Fast or Kimi K3 better for coding?

Kimi K3 scores higher on coding benchmarks: 61.0 versus 32.5 in the Noometry coding category.

### How many benchmarks do Grok 4 Fast and Kimi K3 share?

25 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Kimi K3 has 53.