Model comparison
Claude Opus 4.5 vs Grok 4 Fast
Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 39.4 on the Noometry Index.
Last verified . 29 shared benchmarks.
Summary
- They share 29 benchmarks with published results for both. Claude Opus 4.5 scores higher in 7 categories and Grok 4 Fast in 2 categories; 8 gaps are clear of the uncertainty.
- The widest gap is in knowledge, where Claude Opus 4.5 leads 56.5 to 32.0.
- The biggest single-benchmark swing is Cybench: 82% for Claude Opus 4.5 and 30% for Grok 4 Fast.
Side by side
| Claude Opus 4.5 | Grok 4 Fast | |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 50.5 | 39.4 |
| Released | 2025-11-01 | 2025-09-19 |
| Weights | Proprietary | Proprietary |
| Context window | 200K | — |
| Max output | 64K | — |
| Input $ / M tokens | $5 | — |
| Output $ / M tokens | $25 | — |
| Results tracked | 69 | 30 |
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Category by category
Coding Claude Opus 4.5 leads
Claude Opus 4.5: 54.8 (#27), Grok 4 Fast: 32.5 (#271)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| LMArena WebDev | 1494 | 1159 |
| WeirdML | 63.7% | 42.9% |
| LMArena Coding | 1504 | 1429 |
| SWE-bench Verified | 76.7% | — |
| SWE-bench Verified (bash only) | 76.8% | — |
| SWE-bench Multilingual | 70.7% | — |
| GSO | 26.5% | — |
| ALE-Bench | 1,025 | — |
| AlgoTune | 1.77 | — |
Agentic & Tool Use Claude Opus 4.5 leads
Claude Opus 4.5: 47.3 (#12), Grok 4 Fast: 29.5 (#86)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| τ²-bench Banking | 24.7% | 15.7% |
| Cybench | 82% | 30% |
| LMArena Search | 1180 | 1171 |
| Terminal-Bench | 63.1% | — |
| Berkeley Function Calling Leaderboard | 77.5% | — |
| GDPval | 45.5% | — |
| Remote Labor Index | 3.8% | — |
| τ²-bench Airline | 84% | — |
| τ²-bench Retail | 79.6% | — |
| τ²-bench Telecom | 92.3% | — |
| DeepResearch Bench | 54.8% | — |
| OSWorld | 66.3% | — |
| BALROG | 43.5% | — |
| METR Time Horizons | 75% | — |
| Vending-Bench 2 | 4,967 | — |
Reasoning Claude Opus 4.5 leads
Claude Opus 4.5: 42.6 (#51), Grok 4 Fast: 22.2 (#201)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| ARC-AGI-2 | 37.6% | 5.3% |
| Kagi LLM Benchmark | 80.2% | 66.1% |
| ARC-AGI-1 | 80% | 48.5% |
| LMArena Hard Prompts | 1476 | 1412 |
| DTBench | 89.9% | 82.7% |
| Epoch Capabilities Index | 150.09 | 144.2 |
| ForecastBench | 60.7 | 60.5 |
| SimpleBench | 62% | — |
| NYT Connections (extended) | 52.5% | — |
| Chess Puzzles | 12% | — |
| EnigmaEval | 11.9% | — |
| EBR-Bench | 14.3% | — |
| Mystery Game Puzzles | 22% | — |
| LMCA | 44.5% | — |
Math Too close to call
Claude Opus 4.5: 38.6 (#132), Grok 4 Fast: 38.9 (#123)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Math | 1463 | 1419 |
| FrontierMath (Tiers 1-3) | 34.4% | — |
| FrontierMath Tier 4 | 4.9% | — |
| OTIS Mock AIME 2024-2025 | 86.1% | — |
| ProofBench | 36% | — |
| FrontierMath (Feb 2025 set) | 20.7% | — |
| FrontierMath Tier 4 (v1) | 4.2% | — |
Knowledge Claude Opus 4.5 leads
Claude Opus 4.5: 56.5 (#44), Grok 4 Fast: 32.0 (#214)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| Vectara Hallucination Rate | 10.9% | 19.7% |
| LMArena Expert | 1487 | 1411 |
| GPQA Diamond | 86% | — |
| Humanity's Last Exam | 25.2% | — |
| SimpleQA Verified | 45.7% | — |
Multimodal Not comparable
Claude Opus 4.5: 31.4 (#107), Grok 4 Fast: —
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| GeoBench | 75% | — |
| VPCT | 40% | — |
| Furniture Assembly | 28.3% | — |
| LMArena Document | 1462 | — |
Multilingual Claude Opus 4.5 leads
Claude Opus 4.5: 54.3 (#47), Grok 4 Fast: 51.3 (#111)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Non-English | 1438 | 1396 |
| LMArena Chinese | 1470 | 1457 |
| LMArena French | 1471 | 1431 |
| LMArena German | 1449 | 1383 |
| LMArena Japanese | 1416 | 1352 |
| LMArena Korean | 1424 | 1357 |
| LMArena Russian | 1447 | 1389 |
| LMArena Spanish | 1458 | 1415 |
Instruction Following Claude Opus 4.5 leads
Claude Opus 4.5: 77.5 (#19), Grok 4 Fast: 73.2 (#121)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Instruction Following | 1478 | 1387 |
Long Context Grok 4 Fast leads
Claude Opus 4.5: 46.5 (#22), Grok 4 Fast: 63.2 (#3)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Longer Query | 1480 | 1415 |
| Fiction.LiveBench | — | 94.4% |
| CL-bench | 21.1% | — |
Writing & Preference Claude Opus 4.5 leads
Claude Opus 4.5: 68.1 (#28), Grok 4 Fast: 60.0 (#102)
| Benchmark | Claude Opus 4.5 | Grok 4 Fast |
|---|---|---|
| LMArena Text | 1451 | 1407 |
| LMArena Creative Writing | 1445 | 1387 |
| LMArena Multi-Turn | 1466 | 1414 |
| EQ-Bench Creative Writing | 1687 | — |
Frequently asked questions
Is Claude Opus 4.5 better than Grok 4 Fast?
Claude Opus 4.5 is the stronger model overall, scoring 50.5 to 39.4 on the Noometry Index.
Is Claude Opus 4.5 or Grok 4 Fast better for coding?
Claude Opus 4.5 scores higher on coding benchmarks: 54.8 versus 32.5 in the Noometry coding category.
How many benchmarks do Claude Opus 4.5 and Grok 4 Fast share?
29 benchmarks have published results for both models. Claude Opus 4.5 has 69 scored results on Noometry and Grok 4 Fast has 30.