# Claude Opus 5 vs Grok 4.1 Fast

> Claude Opus 5 is the stronger model overall, scoring 67.7 to 40.9 on the Noometry Index. Grok 4.1 Fast costs 36× less per token, which makes it the better buy when Claude Opus 5's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/claude-opus-5-vs-grok-4-1-fast
- Last updated: 2026-10-10
- Shared benchmarks: 27

## Summary

- They share 27 benchmarks with published results for both. Claude Opus 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 Opus 5 leads 86.1 to 30.9.
- The biggest single-benchmark swing is ProofBench: 99% for Claude Opus 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 $5 / $25 for Claude Opus 5.
- Claude Opus 5 accepts more context: 1M tokens versus 128K.

## Snapshot

| | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 67.7 | 40.9 |
| Rank | 4 | 131 |
| Context | 1M | 128K |
| Input $/M | $5 | $0.20 |
| Output $/M | $25 | $0.50 |
| Weights | Proprietary | Proprietary |

## Coding

- Claude Opus 5: 67.0 (#5)
- Grok 4.1 Fast: 33.8 (#236)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena WebDev | 1694 | 1241 |
| LMArena Coding | 1533 | 1411 |
| ALE-Bench | 2,165 | 394.93 |
| DeepSWE | 73.6% | — |
| FrontierCode | 53.4% | — |
| CursorBench | 46.6% | — |
| FrontierSWE | 52% | — |
| SciCode | 56.4% | — |
| WeirdML | 91.8% | — |

## Agentic & Tool Use

- Claude Opus 5: 55.5 (#1)
- Grok 4.1 Fast: 36.1 (#35)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| τ²-bench Banking | 48.7% | 13.1% |
| Vending-Bench 2 | 11,182 | 1,107 |
| APEX-Agents | 65.8% | — |
| Berkeley Function Calling Leaderboard | — | 69.6% |
| OSWorld 2.0 | 31.4% | — |
| PostTrainBench | 35% | — |
| BALROG | 63.4% | — |
| GBAEval | 79.6% | — |
| GDP.pdf | 24% | — |
| LMArena Search | — | 1171 |

## Reasoning

- Claude Opus 5: 77.1 (#3)
- Grok 4.1 Fast: 42.3 (#45)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| SimpleBench | 80.6% | 56% |
| NYT Connections (extended) | 94.3% | 87.4% |
| LMArena Hard Prompts | 1525 | 1407 |
| DTBench | 97.9% | 87.7% |
| ARC-AGI-2 | 90.4% | — |
| ARC-AGI-1 | 97.5% | — |
| CritPt | 29.1% | — |
| Chess Puzzles | 42% | — |
| EBR-Bench | 45.7% | — |
| Mystery Game Puzzles | 59% | — |
| LMCA | 64.5% | — |
| Bench to the Future 3 | 0.12 | — |
| Epoch Capabilities Index | 162.67 | — |
| ForecastBench | — | 61 |

## Math

- Claude Opus 5: 86.1 (#6)
- Grok 4.1 Fast: 30.9 (#201)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| ProofBench | 99% | 4% |
| LMArena Math | 1533 | 1408 |
| FrontierMath (Tiers 1-3) | 85.6% | — |
| FrontierMath Tier 4 | 73.2% | — |
| MathArena Final-Answer Competitions | — | 60.9% |
| OTIS Mock AIME 2024-2025 | 98.9% | — |

## Knowledge

- Claude Opus 5: 66.8 (#8)
- Grok 4.1 Fast: 32.6 (#203)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Expert | 1558 | 1398 |
| GPQA Diamond | 93.9% | — |
| SimpleQA Verified | 59.9% | — |
| Vectara Hallucination Rate | — | 17.8% |

## Multimodal

- Claude Opus 5: 51.1 (#6)
- Grok 4.1 Fast: 36.3 (#71)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Vision | 1321 | 1201 |
| Blueprint-Bench 2 | 30.4% | — |
| Furniture Assembly | 60.8% | — |
| LMArena Document | 1516 | — |

## Multilingual

- Claude Opus 5: 58.8 (#3)
- Grok 4.1 Fast: 51.1 (#110)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Non-English | 1500 | 1391 |
| LMArena Chinese | 1575 | 1441 |
| LMArena French | 1522 | 1416 |
| LMArena German | 1522 | 1404 |
| LMArena Japanese | 1510 | 1347 |
| LMArena Korean | 1526 | 1361 |
| LMArena Russian | 1507 | 1387 |
| LMArena Spanish | 1519 | 1411 |

## Instruction Following

- Claude Opus 5: 79.3 (#5)
- Grok 4.1 Fast: 72.8 (#127)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Instruction Following | 1516 | 1376 |

## Long Context

- Claude Opus 5: 46.5 (#20)
- Grok 4.1 Fast: 42.4 (#121)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Longer Query | 1516 | 1390 |

## Writing & Preference

- Claude Opus 5: 79.3 (#2)
- Grok 4.1 Fast: 57.4 (#126)

| Benchmark | Claude Opus 5 | Grok 4.1 Fast |
|---|---|---|
| LMArena Text | 1506 | 1408 |
| LMArena Creative Writing | 1491 | 1394 |
| EQ-Bench Creative Writing | 2133 | 1327 |
| LMArena Multi-Turn | 1496 | 1389 |
| EQ-Bench 4 | 1385 | — |

## FAQ

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

Claude Opus 5 is the stronger model overall, scoring 67.7 to 40.9 on the Noometry Index. Grok 4.1 Fast costs 36× less per token, which makes it the better buy when Claude Opus 5's lead doesn't matter for your workload.

### Which is cheaper, Claude Opus 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 Opus 5 lists at $5 and $25.

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

Claude Opus 5 scores higher on coding benchmarks: 67.0 versus 33.8 in the Noometry coding category.

### Which has the bigger context window?

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

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

27 benchmarks have published results for both models. Claude Opus 5 has 57 scored results on Noometry and Grok 4.1 Fast has 32.