Model comparison
Claude Fable 5.1 vs Grok Build 0.1
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 36.4 on the Noometry Index. Grok Build 0.1 costs 16× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Last verified . 2 shared benchmarks.
Summary
- They share 2 benchmarks with published results for both. Claude Fable 5.1 scores higher in 3 categories and Grok Build 0.1 in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Claude Fable 5.1 leads 76.7 to 32.2.
- The biggest single-benchmark swing is CritPt: 31.1% for Claude Fable 5.1 and 9.1% for Grok Build 0.1.
- Grok Build 0.1 is cheaper at $1 / $2 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
- Claude Fable 5.1 accepts more context: 1M tokens versus 256K.
Side by side
| Claude Fable 5.1 | Grok Build 0.1 | |
|---|---|---|
| Provider | Anthropic | xAI |
| Noometry Index | 69.0 | 36.4 |
| Released | 2026-09-01 | 2026-04-16 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 256K |
| Max output | 128K | 256K |
| Input $ / M tokens | $10 | $1 |
| Output $ / M tokens | $50 | $2 |
| Results tracked | 52 | 3 |
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Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 74.7 (#1), Grok Build 0.1: 43.1 (#91)
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| SciCode | 63.1% | 50.2% |
| FrontierCode | 50.9% | — |
| CursorBench | 51.8% | — |
| LMArena WebDev | 1744 | — |
| FrontierSWE | 56.3% | — |
| GSO | 88.2% | — |
| WeirdML | 92.9% | — |
| LMArena Coding | 1528 | — |
| MirrorCode | 73.3% | — |
| ALE-Bench | 2,143 | — |
Agentic & Tool Use Claude Fable 5.1 leads
Claude Fable 5.1: 50.7 (#5), Grok Build 0.1: 22.7 (#129)
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| APEX-Agents | 68.6% | — |
| Remote Labor Index | 17.9% | — |
| GBAEval | — | 2.4% |
| GDP.pdf | 29.6% | — |
| Vending-Bench 2 | 5,422 | — |
Reasoning Claude Fable 5.1 leads
Claude Fable 5.1: 76.7 (#7), Grok Build 0.1: 32.2 (#77)
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| CritPt | 31.1% | 9.1% |
| ARC-AGI-2 | 90% | — |
| NYT Connections (extended) | 90% | — |
| ARC-AGI-1 | 97.5% | — |
| Chess Puzzles | 47% | — |
| EBR-Bench | 57.1% | — |
| LMArena Hard Prompts | 1526 | — |
| Mystery Game Puzzles | 58% | — |
| DTBench | 97.6% | — |
| LMCA | 65.5% | — |
| Epoch Capabilities Index | 164.7 | — |
Math Not comparable
Claude Fable 5.1: 89.6 (#4), Grok Build 0.1: —
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| FrontierMath (Tiers 1-3) | 90.2% | — |
| FrontierMath Tier 4 | 87.8% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| LMArena Math | 1525 | — |
| FrontierMath Erdős | 0% | — |
Knowledge Not comparable
Claude Fable 5.1: 69.6 (#6), Grok Build 0.1: —
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| Humanity's Last Exam | 46.5% | — |
| SimpleQA Verified | 70.8% | — |
| LMArena Expert | 1535 | — |
Multimodal Not comparable
Claude Fable 5.1: 53.9 (#4), Grok Build 0.1: —
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| LMArena Vision | 1318 | — |
| Blueprint-Bench 2 | 41.9% | — |
| Furniture Assembly | 70% | — |
| LMArena Document | 1513 | — |
Multilingual Not comparable
Claude Fable 5.1: 59.1 (#3), Grok Build 0.1: —
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| LMArena Non-English | 1507 | — |
| LMArena Chinese | 1586 | — |
| LMArena French | 1525 | — |
| LMArena German | 1500 | — |
| LMArena Japanese | 1543 | — |
| LMArena Korean | 1534 | — |
| LMArena Russian | 1521 | — |
| LMArena Spanish | 1516 | — |
Instruction Following Not comparable
Claude Fable 5.1: 79.2 (#6), Grok Build 0.1: —
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| LMArena Instruction Following | 1517 | — |
Long Context Not comparable
Claude Fable 5.1: 46.7 (#20), Grok Build 0.1: —
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| LMArena Longer Query | 1522 | — |
Writing & Preference Not comparable
Claude Fable 5.1: 79.2 (#2), Grok Build 0.1: —
| Benchmark | Claude Fable 5.1 | Grok Build 0.1 |
|---|---|---|
| LMArena Text | 1510 | — |
| LMArena Creative Writing | 1507 | — |
| EQ-Bench Creative Writing | 2162 | — |
| LMArena Multi-Turn | 1492 | — |
Frequently asked questions
Is Claude Fable 5.1 better than Grok Build 0.1?
Claude Fable 5.1 is the stronger model overall, scoring 69.0 to 36.4 on the Noometry Index. Grok Build 0.1 costs 16× less per token, which makes it the better buy when Claude Fable 5.1's lead doesn't matter for your workload.
Which is cheaper, Claude Fable 5.1 or Grok Build 0.1?
Grok Build 0.1 is cheaper. It lists at $1 per million input tokens and $2 per million output tokens; Claude Fable 5.1 lists at $10 and $50.
Is Claude Fable 5.1 or Grok Build 0.1 better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 74.7 versus 43.1 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5.1 does, with 1M tokens against 256K.
How many benchmarks do Claude Fable 5.1 and Grok Build 0.1 share?
2 benchmarks have published results for both models. Claude Fable 5.1 has 52 scored results on Noometry and Grok Build 0.1 has 3.