# Claude Sonnet 5 vs Grok 4.1 Fast

> Claude Sonnet 5 is the stronger model overall, scoring 54.6 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 15× less per token, which makes it the better buy when Claude Sonnet 5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-sonnet-5-vs-grok-4-1-fast
- Last updated: 2026-10-10
- Shared benchmarks: 28

## Summary

- They share 28 benchmarks with published results for both. Claude Sonnet 5 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 math, where Claude Sonnet 5 leads 66.2 to 31.9.
- The biggest single-benchmark swing is ProofBench: 77% for Claude Sonnet 5 and 4% for Grok 4.1 Fast.
- Grok 4.1 Fast is cheaper at $0.20 / $0.50 per million input/output tokens, against $2 / $10 for Claude Sonnet 5.
- Claude Sonnet 5 accepts more context: 1M tokens versus 128K.

## Snapshot

| | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 54.6 | 41.4 |
| Rank | 29 | 136 |
| Context | 1M | 128K |
| Input $/M | $2 | $0.20 |
| Output $/M | $10 | $0.50 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Sonnet 5: 55.5 (#26)
- Grok 4.1 Fast: 34.1 (#245)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena WebDev | 1541 | 1242 |
| LMArena Coding | 1483 | 1411 |
| ALE-Bench | 1,463 | 394.93 |
| DeepSWE | 53.8% | — |
| FrontierCode | 42.7% | — |
| CursorBench | 34.1% | — |
| SciCode | 54.3% | — |
| GSO | 37.3% | — |
| WeirdML | 68.8% | — |

## Agentic & Tool Use

- Claude Sonnet 5: 42.8 (#18)
- Grok 4.1 Fast: 36.3 (#39)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Search | 1194 | 1171 |
| Vending-Bench 2 | 6,378 | 1,107 |
| APEX-Agents | 54.5% | — |
| Berkeley Function Calling Leaderboard | — | 69.6% |
| τ²-bench Banking | — | 13.1% |
| GBAEval | 65.3% | — |

## Reasoning

- Claude Sonnet 5: 49.1 (#39)
- Grok 4.1 Fast: 43.4 (#49)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| SimpleBench | 60.6% | 56% |
| NYT Connections (extended) | 75.1% | 87.4% |
| LMArena Hard Prompts | 1461 | 1407 |
| DTBench | 92.5% | 87.7% |
| ForecastBench | 61.1 | 61 |
| CritPt | 16.9% | — |
| Chess Puzzles | 35% | — |
| Mystery Game Puzzles | 35% | — |
| LMCA | 50% | — |
| Surface Evolver Bench | 60% | — |
| Bench to the Future 3 | 0.14 | — |
| Epoch Capabilities Index | 156.21 | — |

## Math

- Claude Sonnet 5: 66.2 (#27)
- Grok 4.1 Fast: 31.9 (#221)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| ProofBench | 77% | 4% |
| LMArena Math | 1467 | 1408 |
| FrontierMath (Tiers 1-3) | 65.6% | — |
| FrontierMath Tier 4 | 29.3% | — |
| MathArena Final-Answer Competitions | — | 60.9% |
| OTIS Mock AIME 2024-2025 | 94.7% | — |

## Knowledge

- Claude Sonnet 5: 55.6 (#47)
- Grok 4.1 Fast: 33.1 (#207)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Expert | 1490 | 1399 |
| GPQA Diamond | 90.5% | — |
| SimpleQA Verified | 33.7% | — |
| Vectara Hallucination Rate | — | 17.8% |

## Multimodal

- Claude Sonnet 5: 42.4 (#31)
- Grok 4.1 Fast: 37.0 (#76)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | 1274 | 1201 |
| Blueprint-Bench 2 | 24.9% | — |
| LMArena Document | 1466 | — |

## Multilingual

- Claude Sonnet 5: 53.8 (#55)
- Grok 4.1 Fast: 51.0 (#114)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1431 | 1391 |
| LMArena Chinese | 1477 | 1441 |
| LMArena French | 1460 | 1415 |
| LMArena German | 1440 | 1404 |
| LMArena Japanese | 1422 | 1349 |
| LMArena Korean | 1411 | 1361 |
| LMArena Russian | 1451 | 1387 |
| LMArena Spanish | 1437 | 1413 |

## Instruction Following

- Claude Sonnet 5: 76.3 (#41)
- Grok 4.1 Fast: 72.7 (#133)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1452 | 1376 |

## Long Context

- Claude Sonnet 5: 44.8 (#55)
- Grok 4.1 Fast: 42.4 (#126)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1463 | 1390 |

## Writing & Preference

- Claude Sonnet 5: 69.2 (#25)
- Grok 4.1 Fast: 57.2 (#131)

| Benchmark | Claude Sonnet 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1442 | 1408 |
| LMArena Creative Writing | 1416 | 1394 |
| EQ-Bench Creative Writing | 1794 | 1327 |
| LMArena Multi-Turn | 1454 | 1389 |
| EQ-Bench 4 | 1236 | — |

## FAQ

### Is Claude Sonnet 5 better than Grok 4.1 Fast?

Claude Sonnet 5 is the stronger model overall, scoring 54.6 to 41.4 on the Noometry Index. Grok 4.1 Fast costs 15× less per token, which makes it the better buy when Claude Sonnet 5's lead doesn't matter for your workload.

### Which is cheaper, Claude Sonnet 5 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; Claude Sonnet 5 lists at $2 and $10.

### Is Claude Sonnet 5 or Grok 4.1 Fast better for coding?

Claude Sonnet 5 scores higher on coding benchmarks: 55.5 versus 34.1 in the Noometry coding category.

### Which has the bigger context window?

Claude Sonnet 5 does, with 1M tokens against 128K.

### How many benchmarks do Claude Sonnet 5 and Grok 4.1 Fast share?

28 benchmarks have published results for both models. Claude Sonnet 5 has 51 scored results on Noometry and Grok 4.1 Fast has 32.