# Gemini 3.8 Flash vs Grok 4.1 Fast

> Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 5.5× less per token, which makes it the better buy when Gemini 3.8 Flash's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gemini-3-8-flash-vs-grok-4-1-fast
- Last updated: 2026-10-10
- Shared benchmarks: 25

## Summary

- They share 25 benchmarks with published results for both. Gemini 3.8 Flash scores higher in 10 categories and Grok 4.1 Fast in 0 categories; 10 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Gemini 3.8 Flash leads 74.8 to 33.1.
- The biggest single-benchmark swing is ProofBench: 48% for Gemini 3.8 Flash and 4% for Grok 4.1 Fast.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $0.75 / $3.75 for Gemini 3.8 Flash.
- Gemini 3.8 Flash accepts more context: 1.05M tokens versus 128K.

## Snapshot

| | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| Provider | Google | xAI |
| Noometry Index | 61.8 | 41.4 |
| Rank | 11 | 136 |
| Context | 1.05M | 128K |
| Input $/M | $0.75 | $0.20 |
| Output $/M | $3.75 | $0.50 |
| Weights | Proprietary | Proprietary |

## Coding

- Gemini 3.8 Flash: 59.2 (#15)
- Grok 4.1 Fast: 34.1 (#245)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena WebDev | 1584 | 1242 |
| LMArena Coding | 1510 | 1411 |
| ALE-Bench | 1,270 | 394.93 |
| DeepSWE | 73.8% | — |
| FrontierCode | 41.2% | — |
| CursorBench | 39.6% | — |
| FrontierSWE | 19.6% | — |
| SciCode | 56.6% | — |
| WeirdML | 84.8% | — |

## Agentic & Tool Use

- Gemini 3.8 Flash: 41.8 (#21)
- Grok 4.1 Fast: 36.3 (#39)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| Vending-Bench 2 | 5,094 | 1,107 |
| APEX-Agents | 64.3% | — |
| Berkeley Function Calling Leaderboard | — | 69.6% |
| Remote Labor Index | 5.8% | — |
| τ²-bench Banking | — | 13.1% |
| GDP.pdf | 23.4% | — |
| LMArena Search | — | 1171 |

## Reasoning

- Gemini 3.8 Flash: 76.9 (#5)
- Grok 4.1 Fast: 43.4 (#49)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| NYT Connections (extended) | 97.4% | 87.4% |
| LMArena Hard Prompts | 1508 | 1407 |
| DTBench | 95.7% | 87.7% |
| ARC-AGI-2 | 89.2% | — |
| SimpleBench | — | 56% |
| ARC-AGI-1 | 98.5% | — |
| CritPt | 18.3% | — |
| Chess Puzzles | 61% | — |
| Mystery Game Puzzles | 47% | — |
| LMCA | 52.9% | — |
| Surface Evolver Bench | 76.9% | — |
| Epoch Capabilities Index | 156.71 | — |
| ForecastBench | — | 61 |

## Math

- Gemini 3.8 Flash: 65.3 (#28)
- Grok 4.1 Fast: 31.9 (#221)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| ProofBench | 48% | 4% |
| LMArena Math | 1528 | 1408 |
| FrontierMath (Tiers 1-3) | 68.4% | — |
| FrontierMath Tier 4 | 22% | — |
| MathArena Final-Answer Competitions | — | 60.9% |
| OTIS Mock AIME 2024-2025 | 98.9% | — |

## Knowledge

- Gemini 3.8 Flash: 74.8 (#2)
- Grok 4.1 Fast: 33.1 (#207)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Expert | 1524 | 1399 |
| GPQA Diamond | 95.4% | — |
| Humanity's Last Exam | 44.5% | — |
| SimpleQA Verified | 69.7% | — |
| Vectara Hallucination Rate | — | 17.8% |

## Multimodal

- Gemini 3.8 Flash: 40.7 (#45)
- Grok 4.1 Fast: 37.0 (#76)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | 1314 | 1201 |
| Blueprint-Bench 2 | 38.6% | — |
| Furniture Assembly | 31.7% | — |

## Multilingual

- Gemini 3.8 Flash: 58.0 (#5)
- Grok 4.1 Fast: 51.0 (#114)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1491 | 1391 |
| LMArena Chinese | 1554 | 1441 |
| LMArena French | 1498 | 1415 |
| LMArena German | 1493 | 1404 |
| LMArena Japanese | 1502 | 1349 |
| LMArena Korean | 1459 | 1361 |
| LMArena Russian | 1515 | 1387 |
| LMArena Spanish | 1485 | 1413 |

## Instruction Following

- Gemini 3.8 Flash: 78.0 (#13)
- Grok 4.1 Fast: 72.7 (#133)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1490 | 1376 |

## Long Context

- Gemini 3.8 Flash: 46.3 (#24)
- Grok 4.1 Fast: 42.4 (#126)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1508 | 1390 |

## Writing & Preference

- Gemini 3.8 Flash: 72.2 (#15)
- Grok 4.1 Fast: 57.2 (#131)

| Benchmark | Gemini 3.8 Flash | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1499 | 1408 |
| LMArena Creative Writing | 1492 | 1394 |
| EQ-Bench Creative Writing | 1748 | 1327 |
| LMArena Multi-Turn | 1501 | 1389 |

## FAQ

### Is Gemini 3.8 Flash better than Grok 4.1 Fast?

Gemini 3.8 Flash is the stronger model overall, scoring 61.8 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 5.5× less per token, which makes it the better buy when Gemini 3.8 Flash's lead doesn't matter for your workload.

### Which is cheaper, Gemini 3.8 Flash or Grok 4.1 Fast?

Grok 4.1 Fast is cheaper. It lists at $0.20 per million input tokens and $0.50 per million output tokens; Gemini 3.8 Flash lists at $0.75 and $3.75.

### Is Gemini 3.8 Flash or Grok 4.1 Fast better for coding?

Gemini 3.8 Flash scores higher on coding benchmarks: 59.2 versus 34.1 in the Noometry coding category.

### Which has the bigger context window?

Gemini 3.8 Flash does, with 1.05M tokens against 128K.

### How many benchmarks do Gemini 3.8 Flash and Grok 4.1 Fast share?

25 benchmarks have published results for both models. Gemini 3.8 Flash has 50 scored results on Noometry and Grok 4.1 Fast has 32.