# GPT-4.5 vs Grok 4 Fast

> Grok 4 Fast is the stronger model overall, scoring 39.0 to 36.9 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-4-5-vs-grok-4-fast
- Last updated: 2026-10-10
- Shared benchmarks: 23

## Summary

- They share 23 benchmarks with published results for both. GPT-4.5 scores higher in 3 categories and Grok 4 Fast in 6 categories; 7 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 40.4.
- The biggest single-benchmark swing is ARC-AGI-1: 10.3% for GPT-4.5 and 48.5% for Grok 4 Fast.

## Snapshot

| | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| Provider | OpenAI | xAI |
| Noometry Index | 36.9 | 39.0 |
| Rank | 200 | 164 |
| Context | — | — |
| Input $/M | — | — |
| Output $/M | — | — |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-4.5: 41.8 (#102)
- Grok 4 Fast: 32.3 (#264)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| WeirdML | 39.4% | 42.9% |
| LMArena Coding | 1397 | 1429 |
| Aider Polyglot | 44.9% | — |
| LMArena WebDev | — | 1160 |
| LiveBench Coding | 75.2% | — |

## Agentic & Tool Use

- GPT-4.5: 27.6 (#92)
- Grok 4 Fast: 29.3 (#80)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| Cybench | 17.5% | 30% |
| τ²-bench Banking | — | 15.7% |
| LMArena Search | — | 1171 |

## Reasoning

- GPT-4.5: 14.1 (#320)
- Grok 4 Fast: 22.5 (#179)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| ARC-AGI-2 | 0.8% | 5.3% |
| ARC-AGI-1 | 10.3% | 48.5% |
| LMArena Hard Prompts | 1404 | 1413 |
| Epoch Capabilities Index | 136.74 | 144.21 |
| ForecastBench | 61.7 | 60.5 |
| SimpleBench | 34.5% | — |
| Kagi LLM Benchmark | — | 66.1% |
| EnigmaEval | 3.2% | — |
| LiveBench Reasoning | 71.1% | — |
| DTBench | — | 82.7% |
| LiveBench Data Analysis | 64.3% | — |
| LiveBench | 69% | — |

## Math

- GPT-4.5: 31.0 (#200)
- Grok 4 Fast: 36.1 (#126)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Math | 1412 | 1419 |
| OTIS Mock AIME 2024-2025 | 37.8% | — |
| LiveBench Math | 69.3% | — |
| MATH Level 5 | 78.6% | — |

## Knowledge

- GPT-4.5: 32.4 (#205)
- Grok 4 Fast: 31.5 (#211)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Expert | 1394 | 1411 |
| GPQA Diamond | 68.7% | — |
| Humanity's Last Exam | 5.4% | — |
| Confabulations | 13.6% | — |
| Vectara Hallucination Rate | — | 19.7% |

## Multimodal

- GPT-4.5: 37.0 (#68)
- Grok 4 Fast: —

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Vision | 1195 | — |
| VPCT | 45% | — |

## Multilingual

- GPT-4.5: 52.7 (#78)
- Grok 4 Fast: 51.5 (#106)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Non-English | 1413 | 1397 |
| LMArena Chinese | 1421 | 1458 |
| LMArena French | 1417 | 1433 |
| LMArena German | 1457 | 1383 |
| LMArena Japanese | 1416 | 1358 |
| LMArena Korean | 1392 | 1359 |
| LMArena Russian | 1419 | 1387 |
| LMArena Spanish | — | 1414 |

## Instruction Following

- GPT-4.5: 72.8 (#129)
- Grok 4 Fast: 73.4 (#116)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Instruction Following | 1404 | 1388 |
| LiveBench Instruction Following | 72.3% | — |

## Long Context

- GPT-4.5: 40.4 (#150)
- Grok 4 Fast: 63.2 (#3)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| Fiction.LiveBench | 63.9% | 94.4% |
| LMArena Longer Query | 1406 | 1415 |

## Writing & Preference

- GPT-4.5: 57.1 (#129)
- Grok 4 Fast: 60.2 (#96)

| Benchmark | GPT-4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Text | 1417 | 1407 |
| LMArena Creative Writing | 1394 | 1388 |
| LMArena Multi-Turn | 1444 | 1414 |
| Short-Story Creative Writing | 75.6% | — |
| EQ-Bench Creative Writing | 1258 | — |
| LiveBench Language | 61.5% | — |

## FAQ

### Is GPT-4.5 better than Grok 4 Fast?

Grok 4 Fast is the stronger model overall, scoring 39.0 to 36.9 on the Noometry Index.

### Is GPT-4.5 or Grok 4 Fast better for coding?

GPT-4.5 scores higher on coding benchmarks: 41.8 versus 32.3 in the Noometry coding category.

### How many benchmarks do GPT-4.5 and Grok 4 Fast share?

23 benchmarks have published results for both models. GPT-4.5 has 42 scored results on Noometry and Grok 4 Fast has 30.