# Gemini 3.1 Pro Preview vs Grok 4.1 Fast

> Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 16× less per token, which makes it the better buy when Gemini 3.1 Pro Preview's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gemini-3-1-pro-preview-vs-grok-4-1-fast
- Last updated: 2026-10-10
- Shared benchmarks: 31

## Summary

- They share 31 benchmarks with published results for both. Gemini 3.1 Pro Preview scores higher in 10 categories and Grok 4.1 Fast in 0 categories; 9 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Gemini 3.1 Pro Preview leads 71.8 to 33.1.
- The biggest single-benchmark swing is MathArena Final-Answer Competitions: 86.5% for Gemini 3.1 Pro Preview and 60.9% for Grok 4.1 Fast.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $2 / $12 for Gemini 3.1 Pro Preview.
- Gemini 3.1 Pro Preview accepts more context: 1.05M tokens versus 128K.

## Snapshot

| | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| Provider | Google | xAI |
| Noometry Index | 56.7 | 41.4 |
| Rank | 23 | 136 |
| Context | 1.05M | 128K |
| Input $/M | $2 | $0.20 |
| Output $/M | $12 | $0.50 |
| Weights | Proprietary | Proprietary |

## Coding

- Gemini 3.1 Pro Preview: 42.5 (#99)
- Grok 4.1 Fast: 34.1 (#245)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| LMArena WebDev | 1447 | 1242 |
| LMArena Coding | 1484 | 1411 |
| ALE-Bench | 1,161 | 394.93 |
| SWE-bench Verified | 75.6% | — |
| DeepSWE | 11.7% | — |
| SciCode | 58.9% | — |
| GSO | 22.6% | — |
| WeirdML | 72.1% | — |
| MirrorCode | 8.9% | — |
| AlgoTune | 2.02 | — |

## Agentic & Tool Use

- Gemini 3.1 Pro Preview: 37.7 (#34)
- Grok 4.1 Fast: 36.3 (#39)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| τ²-bench Banking | 26% | 13.1% |
| LMArena Search | 1211 | 1171 |
| Vending-Bench 2 | 3,774 | 1,107 |
| Terminal-Bench | 80.2% | — |
| APEX-Agents | 35.3% | — |
| Berkeley Function Calling Leaderboard | — | 69.6% |
| DeepResearch Bench | 47.8% | — |
| PostTrainBench | 22% | — |
| BALROG | 57% | — |
| ExploitBench | 26.1% | — |
| GBAEval | 0.8% | — |
| GDP.pdf | 17% | — |
| METR Time Horizons | 77% | — |

## Reasoning

- Gemini 3.1 Pro Preview: 71.7 (#12)
- Grok 4.1 Fast: 43.4 (#49)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| SimpleBench | 79.6% | 56% |
| NYT Connections (extended) | 97.4% | 87.4% |
| LMArena Hard Prompts | 1485 | 1407 |
| DTBench | 97.1% | 87.7% |
| ForecastBench | 59 | 61 |
| ARC-AGI-2 | 77.1% | — |
| ARC-AGI-1 | 98% | — |
| CritPt | 17.7% | — |
| Chess Puzzles | 55% | — |
| EnigmaEval | 36.8% | — |
| Thematic Generalization | 79.4% | — |
| EBR-Bench | 14.3% | — |
| Mystery Game Puzzles | 34% | — |
| LMCA | 53.8% | — |
| Epoch Capabilities Index | 154.77 | — |

## Math

- Gemini 3.1 Pro Preview: 62.1 (#34)
- Grok 4.1 Fast: 31.9 (#221)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| MathArena Final-Answer Competitions | 86.5% | 60.9% |
| ProofBench | 26% | 4% |
| LMArena Math | 1485 | 1408 |
| FrontierMath (Tiers 1-3) | 59.6% | — |
| FrontierMath Tier 4 | 26.8% | — |
| OTIS Mock AIME 2024-2025 | 95.6% | — |
| FrontierMath (Feb 2025 set) | 36.9% | — |
| FrontierMath Tier 4 (v1) | 16.7% | — |

## Knowledge

- Gemini 3.1 Pro Preview: 71.8 (#3)
- Grok 4.1 Fast: 33.1 (#207)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| Vectara Hallucination Rate | 10.4% | 17.8% |
| LMArena Expert | 1485 | 1399 |
| GPQA Diamond | 94.4% | — |
| Humanity's Last Exam | 46.4% | — |
| SimpleQA Verified | 73.5% | — |

## Multimodal

- Gemini 3.1 Pro Preview: 37.9 (#69)
- Grok 4.1 Fast: 37.0 (#76)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | 1296 | 1201 |
| Blueprint-Bench 2 | 26.5% | — |
| Furniture Assembly | 26.7% | — |
| LMArena Document | 1444 | — |

## Multilingual

- Gemini 3.1 Pro Preview: 57.0 (#12)
- Grok 4.1 Fast: 51.0 (#114)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1477 | 1391 |
| LMArena Chinese | 1529 | 1441 |
| LMArena French | 1487 | 1415 |
| LMArena German | 1491 | 1404 |
| LMArena Japanese | 1493 | 1349 |
| LMArena Korean | 1455 | 1361 |
| LMArena Russian | 1498 | 1387 |
| LMArena Spanish | 1479 | 1413 |

## Instruction Following

- Gemini 3.1 Pro Preview: 77.0 (#32)
- Grok 4.1 Fast: 72.7 (#133)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1466 | 1376 |

## Long Context

- Gemini 3.1 Pro Preview: 47.4 (#18)
- Grok 4.1 Fast: 42.4 (#126)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1483 | 1390 |
| CL-bench | 20.8% | — |
| CL-bench Life | 16.9% | — |

## Writing & Preference

- Gemini 3.1 Pro Preview: 66.1 (#37)
- Grok 4.1 Fast: 57.2 (#131)

| Benchmark | Gemini 3.1 Pro Preview | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1481 | 1408 |
| LMArena Creative Writing | 1482 | 1394 |
| EQ-Bench Creative Writing | 1491 | 1327 |
| LMArena Multi-Turn | 1488 | 1389 |
| EQ-Bench 4 | 1142 | — |

## FAQ

### Is Gemini 3.1 Pro Preview better than Grok 4.1 Fast?

Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 16× less per token, which makes it the better buy when Gemini 3.1 Pro Preview's lead doesn't matter for your workload.

### Which is cheaper, Gemini 3.1 Pro Preview 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 3.1 Pro Preview lists at $2 and $12.

### Is Gemini 3.1 Pro Preview or Grok 4.1 Fast better for coding?

Gemini 3.1 Pro Preview scores higher on coding benchmarks: 42.5 versus 34.1 in the Noometry coding category.

### Which has the bigger context window?

Gemini 3.1 Pro Preview does, with 1.05M tokens against 128K.

### How many benchmarks do Gemini 3.1 Pro Preview and Grok 4.1 Fast share?

31 benchmarks have published results for both models. Gemini 3.1 Pro Preview has 71 scored results on Noometry and Grok 4.1 Fast has 32.