Claude Fable 5.1 vs Grok 4.5
Claude Fable 5.1 
Grok 4.5 Verdict
- Claude Fable 5.1 (xhigh) leads on quality: 70.3 vs 63.4.
- Claude Fable 5.1 (xhigh) is stronger in coding, composite, knowledge, long context, reasoning.
- Grok 4.5 is stronger in agents & tools, human preference, multimodal.
- Grok 4.5 is 6.7× cheaper ($3.00 vs $20.00 per 1M blended).
| Metric | Claude Fable 5.1 (xhigh) | Grok 4.5 |
|---|---|---|
| BenchLeader Index | 70.3 | 63.4 |
| Coding score | 71.3 | 59.9 |
| Composite score | 95.0 | 66.0 |
| Knowledge score | 84.1 | 76.0 |
| Long context score | 68.1 | 66.2 |
| Reasoning score | 76.4 | 68.9 |
| Agents & tools score | – | 58.6 |
| Human preference score | – | 66.9 |
| Multimodal score | – | 64.8 |
| Blended price $/M | $20.00 | $3.00 |
| Output speed | 58 tok/s | 56 tok/s |
| Time to first answer | 132.0 s | 12.7 s |
| Context window | 1M | 500k |
| Humanity's Last Exam | 46.5% | – |
| SimpleBench | – | 70.0% |
| SciCode | 60.1% | – |
| WeirdML | – | 46.4% |
| APEX-Agents | – | 34.2% |
| FrontierCode | – | 42.4% |
| Epoch Capabilities Index | – | 153.9 |
| LMArena Text | – | 1471 |
| LMArena Hard Prompts | – | 1495 |
| LMArena Coding | – | 1523 |
| LMArena WebDev | – | 1556 |
| LMArena Vision | – | 1291 |
| LMArena Agent | – | 3.9 |
| LiveBench | – | 75.8% |
| LiveBench Reasoning | – | 87.2% |
| LiveBench Coding | – | 68.6% |
| LiveBench Agentic Coding | – | 56.5% |
| LiveBench Mathematics | – | 90.8% |
| LiveBench Data Analysis | – | 73.0% |
| LiveBench Language | – | 82.8% |
| AA Intelligence Index | 53.2 | 39.1 |
| AA-LCR | 83.0% | 79.3% |
| MMMU-Pro | – | 80.4% |
| AA-Omniscience | 42.4 | 25.3 |
| GPQA Diamond (AA) | 93.4% | 93.1% |
| Humanity's Last Exam (AA) | 58.7% | 42.7% |
| SciCode (AA) | 60.9% | 55.0% |
| Kagi LLM Benchmark | – | 83.5% |
| ARC-AGI-1 | 96.5% | – |
| ARC-AGI-2 | 90.0% | – |
Data as of 2026-09-09. Best configuration of each model; every score links to its source on the model pages.