# Claude Fable 5.1 vs Grok 4.20

> Side-by-side benchmark comparison for Claude Fable 5.1 and Grok 4.20 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-fable-5-1-vs-grok-4-20-beta
- Last updated: October 17, 2026

- Shared sourced benchmarks: 8
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Claude Fable 5.1 leads by point estimate. Conditional score ranges do not establish rank confidence. Choose using the category evidence and your own workload tests.

## Summary

- Claude Fable 5.1 has the higher overall point estimate 83.18 to 57.43. Conditional score ranges do not establish rank confidence.
- The clearest category separation is in agentic, where the averages are 80.9 for Claude Fable 5.1 and 25.1 for Grok 4.20.
- The biggest single benchmark swing is Terminal-Bench 2.1 (Vals) in Agentic, with scores of 85.0% and 44.2%.
- Grok 4.20 is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Grok 4.20 also has the larger context window at 2M.

## Model Snapshot

| Property | Claude Fable 5.1 | Grok 4.20 |
|----------|----------|----------|
| Creator | Anthropic | xAI |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 2M |
| Overall Score | 83.18 | 57.43 |
| Benchmarks Covered | 33 | 24 |
| Pricing (input/output) | $10.00 / $50.00 | $1.25 / $2.50 |

## Category Breakdown

### Agentic

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 80.9 (Supported · #2/128)
- Grok 4.20 public-lane score: 25.1 (Supported · #103/128)

| Benchmark | Claude Fable 5.1 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 4.0 | 55.80% | Coming soon | Coming soon |
| Terminal-Bench-Science 0.1 | 52.6% | Coming soon | Coming soon |
| OSWorld 2.0 | 41.7% | Coming soon | Coming soon |
| AutomationBench | 31.4% | Coming soon | Coming soon |
| Toolathlon-Verified | 77.8% | Coming soon | Coming soon |
| Toolathlon Verified Pass@3 | 81.5% | Coming soon | Coming soon |
| Toolathlon Verified Pass³ | 73.1% | Coming soon | Coming soon |
| Toolathlon Verified avg. turns | 23.7 turns | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 85.0% | 44.2% | Claude Fable 5.1 |
| ApprenticeBench | 72% | Coming soon | Coming soon |
| CWE-bench v1 | 58.0% | Coming soon | Coming soon |
| MazeBench | 10% | 0% | Claude Fable 5.1 |
| Terminal-Bench 2.0 | Coming soon | 47.1% | Coming soon |
| DeepSearchQA | Coming soon | 62.8% | Coming soon |
| Gert Labs | Coming soon | 38.36% | Coming soon |

### Coding

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 76.8 (Supported · #3/150)
- Grok 4.20 public-lane score: 21.6 (Supported · #118/150)

| Benchmark | Claude Fable 5.1 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Bug Hunt Bench | 43.0 fixes | Coming soon | Coming soon |
| SWE-bench Pro | 81.2% | 51.8% | Claude Fable 5.1 |
| SWE Multilingual | 89.1% | Coming soon | Coming soon |
| SWE Multimodal | 54.7% | Coming soon | Coming soon |
| DeepSWE | 67.4% | Coming soon | Coming soon |
| FrontierSWE v2 | 56.3% | Coming soon | Coming soon |
| ProgramBench | 87.6% | Coming soon | Coming soon |
| CursorBench 3.2 | 73.4% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 90.5% | 84.3% | Claude Fable 5.1 |
| CursorBench 4.0 | 51.8% | Coming soon | Coming soon |
| PostTrainBench v1.1 | 40.2% | Coming soon | Coming soon |
| LiveCodeBench Pro | Coming soon | 74.2% | Coming soon |
| SWE-bench Verified | Coming soon | 76.7% | Coming soon |
| Vibe Code Bench | Coming soon | 4.06% | Coming soon |
| SWE-bench (Vals) | Coming soon | 72.2% | Coming soon |

### Reasoning

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: 85.2 (#4/28)
- Grok 4.20 public-lane score: 44.9 (Unranked · 2 rankable rows)

| Benchmark | Claude Fable 5.1 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | 97.50% | Coming soon | Coming soon |
| ARC-AGI-2 | 90% | 53.3% | Claude Fable 5.1 |
| GraphWalks BFS 256K–1M | 65.0% | Coming soon | Coming soon |
| ARC-AGI-3 | Coming soon | 0.1% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: Coming soon
- Grok 4.20 public-lane score: 53.4 (#47/54)

| Benchmark | Claude Fable 5.1 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| MMMU-Pro | Coming soon | 75.2% | Coming soon |
| CharXiv | Coming soon | 60.9% | Coming soon |
| ERQA | Coming soon | 54.1% | Coming soon |
| SimpleVQA | Coming soon | 57.4% | Coming soon |
| MedXpertQA (MM) | Coming soon | 65.8% | Coming soon |

### Knowledge

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 86.9 (Supported · #2/184)
- Grok 4.20 public-lane score: 53.1 (Supported · #69/184)

| Benchmark | Claude Fable 5.1 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| HLE | 65% | Coming soon | Coming soon |
| HLE w/o tools | 60.9% | 31.6% | Claude Fable 5.1 |
| GPQA Diamond (Vals) | 93.4% | 88.6% | Claude Fable 5.1 |
| MMLU-Pro (Vals) | 92.4% | 86.3% | Claude Fable 5.1 |
| GPQA-D | Coming soon | 88.5% | Coming soon |
| HealthBench Hard | Coming soon | 20.3% | Coming soon |
| MedXpertQA (Text) | Coming soon | 50.2% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: Coming soon
- Grok 4.20 public-lane score: Coming soon

| Benchmark | Claude Fable 5.1 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| Gray Swan IPI (15 attempts) | 1.0% | Coming soon | Coming soon |

### Mathematics

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: 96.8 (Unranked · 2 rankable rows)
- Grok 4.20 public-lane score: Coming soon

| Benchmark | Claude Fable 5.1 | Grok 4.20 | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 90.175% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 87.805% | Coming soon | Coming soon |

## FAQ

### Which is better overall, Claude Fable 5.1 or Grok 4.20?

Claude Fable 5.1 has the higher overall point estimate. Conditional score ranges do not establish rank confidence.

### Where is the biggest gap between Claude Fable 5.1 and Grok 4.20?

The widest category gap is in agentic, where the averages are 80.9 for Claude Fable 5.1 and 25.1 for Grok 4.20.

### How many benchmarks does Claude Fable 5.1 cover on BenchLM?

Claude Fable 5.1 currently has 33 sourced benchmark scores on BenchLM.

### How many benchmarks does Grok 4.20 cover on BenchLM?

Grok 4.20 currently has 24 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Fable 5.1 vs Claude Fable 5](/compare/claude-fable-vs-claude-fable-5-1)
- [Grok 4.20 vs Claude Fable 5](/compare/claude-fable-vs-grok-4-20-beta)
- [Claude Fable 5.1 vs Grok 4.20 Multi-agent](/compare/claude-fable-5-1-vs-grok-4-20-multi-agent-beta)
- [Grok 4.20 vs Grok 4.20 Multi-agent](/compare/grok-4-20-beta-vs-grok-4-20-multi-agent-beta)

## Explore More

- [Claude Fable 5.1 profile](/models/claude-fable-5-1)
- [Grok 4.20 profile](/models/grok-4-20-beta)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)