# Grok 4 Fast vs Nemotron 3.5 Lightning

> Grok 4 Fast and Nemotron 3.5 Lightning score almost the same on the Noometry Index (39.4 vs 40.0), so choose on price, context window or the category you care about most.

- Canonical page: https://noometry.com/compare/grok-4-fast-vs-nemotron-3-5-lightning
- Last updated: 2026-10-12
- Shared benchmarks: 17

## Summary

- They share 17 benchmarks with published results for both. Grok 4 Fast scores higher in 5 categories and Nemotron 3.5 Lightning in 3 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in long context, where Grok 4 Fast leads 63.2 to 39.9.
- Nemotron 3.5 Lightning has downloadable open weights; the other is API-only.

## Snapshot

| | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| Provider | xAI | NVIDIA |
| Noometry Index | 39.4 | 40.0 |
| Rank | 167 | 155 |
| Context | — | 262K |
| Input $/M | — | $0.05 |
| Output $/M | — | $0.20 |
| Weights | Proprietary | Open |

## Coding

- Grok 4 Fast: 32.5 (#271)
- Nemotron 3.5 Lightning: 40.4 (#141)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Coding | 1429 | 1375 |
| LMArena WebDev | 1159 | — |
| WeirdML | 42.9% | — |

## Agentic & Tool Use

- Grok 4 Fast: 29.5 (#86)
- Nemotron 3.5 Lightning: —

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

## Reasoning

- Grok 4 Fast: 22.2 (#201)
- Nemotron 3.5 Lightning: 26.8 (#127)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Hard Prompts | 1412 | 1337 |
| 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)
- Nemotron 3.5 Lightning: 37.5 (#155)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Math | 1419 | 1359 |

## Knowledge

- Grok 4 Fast: 32.0 (#214)
- Nemotron 3.5 Lightning: 37.5 (#154)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Expert | 1411 | 1356 |
| Vectara Hallucination Rate | 19.7% | — |

## Multilingual

- Grok 4 Fast: 51.3 (#111)
- Nemotron 3.5 Lightning: 44.0 (#180)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Non-English | 1396 | 1295 |
| LMArena Chinese | 1457 | 1359 |
| LMArena French | 1431 | 1366 |
| LMArena German | 1383 | 1282 |
| LMArena Japanese | 1352 | 1206 |
| LMArena Korean | 1357 | 1238 |
| LMArena Russian | 1389 | 1253 |
| LMArena Spanish | 1415 | 1345 |

## Instruction Following

- Grok 4 Fast: 73.2 (#121)
- Nemotron 3.5 Lightning: 69.6 (#170)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Instruction Following | 1387 | 1318 |

## Long Context

- Grok 4 Fast: 63.2 (#3)
- Nemotron 3.5 Lightning: 39.9 (#165)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Longer Query | 1415 | 1314 |
| Fiction.LiveBench | 94.4% | — |

## Writing & Preference

- Grok 4 Fast: 60.0 (#102)
- Nemotron 3.5 Lightning: 48.5 (#201)

| Benchmark | Grok 4 Fast | Nemotron 3.5 Lightning |
|---|---|---|
| LMArena Text | 1407 | 1327 |
| LMArena Creative Writing | 1387 | 1254 |
| LMArena Multi-Turn | 1414 | 1328 |
| EQ-Bench Creative Writing | — | 1280 |

## FAQ

### Is Grok 4 Fast better than Nemotron 3.5 Lightning?

Grok 4 Fast and Nemotron 3.5 Lightning score almost the same on the Noometry Index (39.4 vs 40.0), so choose on price, context window or the category you care about most.

### Is Grok 4 Fast or Nemotron 3.5 Lightning better for coding?

Nemotron 3.5 Lightning scores higher on coding benchmarks: 40.4 versus 32.5 in the Noometry coding category.

### How many benchmarks do Grok 4 Fast and Nemotron 3.5 Lightning share?

17 benchmarks have published results for both models. Grok 4 Fast has 30 scored results on Noometry and Nemotron 3.5 Lightning has 18.