Model comparison
Claude Fable 5 vs Grok 4.5
Claude Fable 5 is the stronger model overall, scoring 66.8 to 55.0 on the Noometry Index. Grok 4.5 costs 6.7× less per token, which makes it the better buy when Claude Fable 5's lead doesn't matter for your workload.
Last verified . 52 shared benchmarks.
Summary
- They share 52 benchmarks with published results for both. Claude Fable 5 scores higher in 9 categories and Grok 4.5 in 1 category; 9 gaps are clear of the uncertainty.
- The widest gap is in math, where Claude Fable 5 leads 88.5 to 60.9.
- The biggest single-benchmark swing is FrontierMath Tier 4: 90.2% for Claude Fable 5 and 24.4% for Grok 4.5.
- Grok 4.5 is cheaper at $2 / $6 per million input/output tokens, against $10 / $50 for Claude Fable 5.
- Claude Fable 5 accepts more context: 1M tokens versus 500K.
Side by side
| Claude Fable 5 | Grok 4.5 | |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 66.8 | 55.0 |
| Released | 2026-06-07 | 2026-07-08 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 500K |
| Max output | 128K | 500K |
| Input $ / M tokens | $10 | $2 |
| Output $ / M tokens | $50 | $6 |
| Results tracked | 62 | 52 |
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Category by category
Coding Claude Fable 5 leads
Claude Fable 5: 70.6 (#4), Grok 4.5: 52.2 (#35)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| DeepSWE | 69.9% | 53.8% |
| FrontierCode | 53.5% | 42.4% |
| LMArena WebDev | 1625 | 1553 |
| SciCode | 61% | 54.1% |
| WeirdML | 91.9% | 46.4% |
| LMArena Coding | 1519 | 1474 |
| ALE-Bench | 2,041 | 1,309 |
| FrontierSWE | 47% | — |
| GSO | 78.4% | — |
| MirrorCode | 63.9% | — |
Agentic & Tool Use Claude Fable 5 leads
Claude Fable 5: 54.0 (#2), Grok 4.5: 44.4 (#17)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| APEX-Agents | 63.6% | 56.2% |
| τ²-bench Banking | 39.7% | 47.9% |
| PostTrainBench | 41.8% | 23.4% |
| GBAEval | 74.5% | 65.4% |
| GDP.pdf | 30% | 14% |
| LMArena Search | 1230 | 1213 |
| Vending-Bench 2 | 5,680 | 3,887 |
| Remote Labor Index | 16.1% | — |
Reasoning Claude Fable 5 leads
Claude Fable 5: 76.8 (#6), Grok 4.5: 56.1 (#25)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| ARC-AGI-2 | 89.2% | 52.6% |
| SimpleBench | 81.9% | 70% |
| Kagi LLM Benchmark | 91.4% | 83.5% |
| NYT Connections (extended) | 92.7% | 79.9% |
| ARC-AGI-1 | 98.5% | 87.2% |
| CritPt | 28.6% | 15.4% |
| Chess Puzzles | 41% | 36% |
| LMArena Hard Prompts | 1508 | 1462 |
| DTBench | 98.4% | 96.5% |
| LMCA | 61.1% | 45.2% |
| Surface Evolver Bench | 95% | 74.4% |
| Epoch Capabilities Index | 162.06 | 153.92 |
| EnigmaEval | 39.3% | — |
| EBR-Bench | 39.5% | — |
| Mystery Game Puzzles | 52% | — |
| Bench to the Future 3 | 0.13 | — |
Math Claude Fable 5 leads
Claude Fable 5: 88.5 (#5), Grok 4.5: 60.9 (#35)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 87% | 57.2% |
| FrontierMath Tier 4 | 90.2% | 24.4% |
| OTIS Mock AIME 2024-2025 | 100% | 97.8% |
| ProofBench | 95% | 31% |
| LMArena Math | 1519 | 1459 |
| FrontierMath Erdős | 0% | — |
Knowledge Too close to call
Claude Fable 5: 62.2 (#25), Grok 4.5: 62.3 (#24)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| GPQA Diamond | 85.9% | 93.4% |
| SimpleQA Verified | 70.7% | 48.3% |
| LMArena Expert | 1534 | 1466 |
Multimodal Claude Fable 5 leads
Claude Fable 5: 45.3 (#17), Grok 4.5: 37.6 (#72)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| LMArena Vision | 1324 | 1288 |
| Blueprint-Bench 2 | 38.6% | 27.3% |
| Furniture Assembly | 35.8% | 22.5% |
| LMArena Document | 1496 | 1452 |
Multilingual Claude Fable 5 leads
Claude Fable 5: 57.3 (#9), Grok 4.5: 54.4 (#42)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| LMArena Non-English | 1481 | 1440 |
| LMArena Chinese | 1543 | 1496 |
| LMArena French | 1505 | 1456 |
| LMArena German | 1486 | 1446 |
| LMArena Japanese | 1506 | 1428 |
| LMArena Korean | 1488 | 1404 |
| LMArena Russian | 1504 | 1448 |
| LMArena Spanish | 1498 | 1450 |
Instruction Following Claude Fable 5 leads
Claude Fable 5: 78.6 (#8), Grok 4.5: 76.0 (#48)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| LMArena Instruction Following | 1502 | 1446 |
Long Context Claude Fable 5 leads
Claude Fable 5: 46.3 (#23), Grok 4.5: 44.8 (#56)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| LMArena Longer Query | 1509 | 1463 |
Writing & Preference Claude Fable 5 leads
Claude Fable 5: 75.9 (#5), Grok 4.5: 65.8 (#42)
| Benchmark | Claude Fable 5 | Grok 4.5 |
|---|---|---|
| LMArena Text | 1491 | 1448 |
| LMArena Creative Writing | 1494 | 1442 |
| EQ-Bench Creative Writing | 1943 | 1579 |
| LMArena Multi-Turn | 1504 | 1456 |
| EQ-Bench 4 | 1340 | — |
Frequently asked questions
Is Claude Fable 5 better than Grok 4.5?
Claude Fable 5 is the stronger model overall, scoring 66.8 to 55.0 on the Noometry Index. Grok 4.5 costs 6.7× less per token, which makes it the better buy when Claude Fable 5's lead doesn't matter for your workload.
Which is cheaper, Claude Fable 5 or Grok 4.5?
Grok 4.5 is cheaper. It lists at $2 per million input tokens and $6 per million output tokens; Claude Fable 5 lists at $10 and $50.
Is Claude Fable 5 or Grok 4.5 better for coding?
Claude Fable 5 scores higher on coding benchmarks: 70.6 versus 52.2 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5 does, with 1M tokens against 500K.
How many benchmarks do Claude Fable 5 and Grok 4.5 share?
52 benchmarks have published results for both models. Claude Fable 5 has 62 scored results on Noometry and Grok 4.5 has 52.