# Claude Fable 5.1 vs Claude Opus 4.8

> Side-by-side benchmark comparison for Claude Fable 5.1 and Claude Opus 4.8 across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-fable-5-1-vs-claude-opus-4-8
- Last updated: October 17, 2026

- Shared sourced benchmarks: 17
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Pick Claude Fable 5.1 if you want the stronger benchmark profile. Claude Opus 4.8 only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Claude Fable 5.1 leads overall 83.18 to 70.01.
- The clearest category separation is in reasoning, where the averages are 85.2 for Claude Fable 5.1 and 62.8 for Claude Opus 4.8.
- The biggest single benchmark swing is FrontierMath v2 (Tier 4) in Mathematics, with scores of 87.805% and 56.098%.
- Claude Opus 4.8 is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | Claude Fable 5.1 | Claude Opus 4.8 |
|----------|----------|----------|
| Creator | Anthropic | Anthropic |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1M |
| Overall Score | 83.18 | 70.01 |
| Benchmarks Covered | 33 | 41 |
| Pricing (input/output) | $10.00 / $50.00 | $5.00 / $25.00 |

## Category Breakdown

### Agentic

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 80.9 (Supported · #2/128)
- Claude Opus 4.8 public-lane score: 63.4 (Supported · #19/128)

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | 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% | 20.6% | Claude Fable 5.1 |
| 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% | 71.9% | 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 3.0 | Coming soon | 21.1% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 74.6% | Coming soon |
| BrowseComp | Coming soon | 84.3% | Coming soon |
| DeepSearchQA | Coming soon | 93.1% | Coming soon |
| OSWorld-Verified | Coming soon | 83.4% | Coming soon |
| Finance Agent v2 | Coming soon | 53.9% | Coming soon |
| MCP Atlas | Coming soon | 82.2% | Coming soon |
| Toolathlon | Coming soon | 59.9% | Coming soon |
| Gert Labs | Coming soon | 72.97% | Coming soon |
| ResearchClawBench | Coming soon | 21.1% | Coming soon |

### Coding

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 76.8 (Supported · #3/150)
- Claude Opus 4.8 public-lane score: 60.7 (Supported · #19/150)

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| Bug Hunt Bench | 43.0 fixes | Coming soon | Coming soon |
| SWE-bench Pro | 81.2% | 69.2% | Claude Fable 5.1 |
| SWE Multilingual | 89.1% | 84.4% | Claude Fable 5.1 |
| SWE Multimodal | 54.7% | 38.4% | Claude Fable 5.1 |
| 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% | 62.3% | Claude Fable 5.1 |
| LiveCodeBench (Vals) | 90.5% | 87.8% | Claude Fable 5.1 |
| CursorBench 4.0 | 51.8% | Coming soon | Coming soon |
| PostTrainBench v1.1 | 40.2% | 32.9% | Claude Fable 5.1 |
| SWE-bench Verified | Coming soon | 88.6% | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 74.6% | Coming soon |
| cursorBench31 | Coming soon | 58.4% | Coming soon |
| FrontierCode 1.1 Main | Coming soon | 46.5% | Coming soon |
| SWE-bench (Vals) | Coming soon | 88.6% | Coming soon |

### Reasoning

- Winner: Directional only
- Claude Fable 5.1 public-lane score: 85.2 (#4/28)
- Claude Opus 4.8 public-lane score: 62.8 (#24/28)

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | 97.50% | 92.50% | Claude Fable 5.1 |
| ARC-AGI-2 | 90% | 72.1% | Claude Fable 5.1 |
| GraphWalks BFS 256K–1M | 65.0% | Coming soon | Coming soon |
| ARC-AGI-3 | Coming soon | 1.5% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 91.2 (#5/54)

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| OfficeQA Pro | Coming soon | 66.2% | Coming soon |
| ScreenSpot Pro | Coming soon | 87.9% | Coming soon |
| CharXiv | Coming soon | 89.9% | Coming soon |
| CharXiv w/o tools | Coming soon | 80.5% | Coming soon |

### Knowledge

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 86.9 (Supported · #2/184)
- Claude Opus 4.8 public-lane score: 72 (Supported · #15/184)

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| HLE | 65% | 57.9% | Claude Fable 5.1 |
| HLE w/o tools | 60.9% | 49.8% | Claude Fable 5.1 |
| GPQA Diamond (Vals) | 93.4% | 92.4% | Claude Fable 5.1 |
| MMLU-Pro (Vals) | 92.4% | 89.6% | Claude Fable 5.1 |
| GPQA | Coming soon | 93.6% | Coming soon |
| GPQA-D | Coming soon | 93.6% | Coming soon |

### Multilingual

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: Coming soon

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| INCLUDE | Coming soon | 87.6% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: Coming soon
- Claude Opus 4.8 public-lane score: 75.4 (#65/148)

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | 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)
- Claude Opus 4.8 public-lane score: 84.4 (#1/12)

| Benchmark | Claude Fable 5.1 | Claude Opus 4.8 | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 90.175% | 80.000% | Claude Fable 5.1 |
| FrontierMath v2 (Tier 4) | 87.805% | 56.098% | Claude Fable 5.1 |
| USAMO 2026 | Coming soon | 96.7% | Coming soon |

## FAQ

### Which is better overall, Claude Fable 5.1 or Claude Opus 4.8?

Claude Fable 5.1 is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Fable 5.1 and Claude Opus 4.8?

The widest category gap is in reasoning, where the averages are 85.2 for Claude Fable 5.1 and 62.8 for Claude Opus 4.8.

### 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 Claude Opus 4.8 cover on BenchLM?

Claude Opus 4.8 currently has 41 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Fable 5.1 vs Claude Fable 5](/compare/claude-fable-vs-claude-fable-5-1)
- [Claude Opus 4.8 vs Claude Fable 5](/compare/claude-fable-vs-claude-opus-4-8)
- [Claude Fable 5.1 vs Claude Opus 5.5](/compare/claude-fable-5-1-vs-claude-opus-5-5)
- [Claude Opus 4.8 vs Claude Opus 5.5](/compare/claude-opus-4-8-vs-claude-opus-5-5)

## Explore More

- [Claude Fable 5.1 profile](/models/claude-fable-5-1)
- [Claude Opus 4.8 profile](/models/claude-opus-4-8)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)