# Claude Fable 5 vs Gemini 3.8 Flash

> Side-by-side benchmark comparison for Claude Fable 5 and Gemini 3.8 Flash across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-fable-vs-gemini-3-8-flash
- Last updated: October 17, 2026

- Shared sourced benchmarks: 15
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Pick Claude Fable 5 if you want the stronger benchmark profile. Gemini 3.8 Flash only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Claude Fable 5 leads overall 81.27 to 69.25.
- The clearest category separation is in mathematics, where the averages are 96 for Claude Fable 5 and 69.7 for Gemini 3.8 Flash.
- The biggest single benchmark swing is FrontierMath v2 (Tier 4) in Mathematics, with scores of 90.200% and 21.951%.
- Gemini 3.8 Flash is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | Claude Fable 5 | Gemini 3.8 Flash |
|----------|----------|----------|
| Creator | Anthropic | Google |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M+ | 1M |
| Overall Score | 81.27 | 69.25 |
| Benchmarks Covered | 24 | 31 |
| Pricing (input/output) | $10.00 / $50.00 | $0.75 / $3.75 |

## Category Breakdown

### Agentic

- Winner: Claude Fable 5
- Claude Fable 5 public-lane score: 75.9 (Supported · #6/128)
- Gemini 3.8 Flash public-lane score: 65.9 (Supported · #16/128)

| Benchmark | Claude Fable 5 | Gemini 3.8 Flash | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 3.0 | 34.0% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 84.3% | 89.4% | Gemini 3.8 Flash |
| OSWorld-Verified | 85% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 80.5% | 81.3% | Gemini 3.8 Flash |
| ApprenticeBench | 34% | 24% | Claude Fable 5 |
| MazeBench | 11% | 4% | Claude Fable 5 |
| Finance Agent v2 | Coming soon | 61.4% | Coming soon |
| Terminal-Bench 4.0 | Coming soon | 19.10% | Coming soon |
| OSWorld 2.0 | Coming soon | 59.0% | Coming soon |
| Hermes Index | Coming soon | 38.1% | Coming soon |
| Hermes Bench | Coming soon | 62.2% | Coming soon |

### Coding

- Winner: Claude Fable 5
- Claude Fable 5 public-lane score: 71.3 (Supported · #7/150)
- Gemini 3.8 Flash public-lane score: 61 (Supported · #17/150)

| Benchmark | Claude Fable 5 | Gemini 3.8 Flash | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 95% | Coming soon | Coming soon |
| SWE-bench Pro | 80% | Coming soon | Coming soon |
| FrontierSWE v2 | 47.0% | 19.6% | Claude Fable 5 |
| FrontierCode 1.1 Main | 53.5% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | 84.3% | 89.4% | Gemini 3.8 Flash |
| cursorBench31 | 70.6% | Coming soon | Coming soon |
| CursorBench 3.2 | 70.5% | 69.2% | Claude Fable 5 |
| VulcanBench v3 | 89.5% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 89.8% | 89.5% | Claude Fable 5 |
| SWE-bench (Vals) | 95.0% | 80.0% | Claude Fable 5 |
| DeepSWE | Coming soon | 73.8% | Coming soon |
| CursorBench 4.0 | Coming soon | 39.6% | Coming soon |
| Bug Hunt Bench | Coming soon | 18.0 fixes | Coming soon |

### Reasoning

- Winner: Not comparable
- Claude Fable 5 public-lane score: 84.3 (Unranked · 4 rankable rows)
- Gemini 3.8 Flash public-lane score: 74.3 (#17/28)

| Benchmark | Claude Fable 5 | Gemini 3.8 Flash | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-1 | 98.50% | 98.50% | Tie |
| ARC-AGI-2 | 89.2% | 89.2% | Tie |
| ARC-AGI-3 | Coming soon | 10.4% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Fable 5 public-lane score: 66 (Unranked · 2 rankable rows)
- Gemini 3.8 Flash public-lane score: 87.3 (#9/54)

| Benchmark | Claude Fable 5 | Gemini 3.8 Flash | Winner |
|-----------|-----------|-----------|--------|
| Blueprint-Bench 2 | 38.6% | Coming soon | Coming soon |
| OfficeQA Pro | 57.9% | Coming soon | Coming soon |
| CharXiv w/o tools | Coming soon | 86.2% | Coming soon |
| LVBench | Coming soon | 87.1% | Coming soon |

### Knowledge

- Winner: Claude Fable 5
- Claude Fable 5 public-lane score: 82.5 (Supported · #6/184)
- Gemini 3.8 Flash public-lane score: 73.5 (Supported · #13/184)

| Benchmark | Claude Fable 5 | Gemini 3.8 Flash | Winner |
|-----------|-----------|-----------|--------|
| GPQA Diamond (Vals) | 93.2% | 94.4% | Gemini 3.8 Flash |
| MMLU-Pro (Vals) | 91.5% | 90.2% | Claude Fable 5 |
| HLE-Verified | Coming soon | 54.9% | Coming soon |
| LABBench2 | Coming soon | 86.2% | Coming soon |
| BioMysteryBench (human-solvable) | Coming soon | 88.8% | Coming soon |
| BioMysteryBench (human-difficult) | Coming soon | 56.5% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Claude Fable 5 public-lane score: 77.1 (#62/148)
- Gemini 3.8 Flash public-lane score: Coming soon

| Benchmark | Claude Fable 5 | Gemini 3.8 Flash | Winner |
|-----------|-----------|-----------|--------|
| Gray Swan IPI (15 attempts) | Coming soon | 5.5% | Coming soon |

### Mathematics

- Winner: Not comparable
- Claude Fable 5 public-lane score: 96 (Unranked · 2 rankable rows)
- Gemini 3.8 Flash public-lane score: 69.7 (Unranked · 2 rankable rows)

| Benchmark | Claude Fable 5 | Gemini 3.8 Flash | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 87.018% | 68.421% | Claude Fable 5 |
| FrontierMath v2 (Tier 4) | 90.200% | 21.951% | Claude Fable 5 |

## FAQ

### Which is better overall, Claude Fable 5 or Gemini 3.8 Flash?

Claude Fable 5 is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Fable 5 and Gemini 3.8 Flash?

The widest category gap is in mathematics, where the averages are 96 for Claude Fable 5 and 69.7 for Gemini 3.8 Flash.

### How many benchmarks does Claude Fable 5 cover on BenchLM?

Claude Fable 5 currently has 24 sourced benchmark scores on BenchLM.

### How many benchmarks does Gemini 3.8 Flash cover on BenchLM?

Gemini 3.8 Flash currently has 31 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Fable 5 vs Claude Fable 5.1](/compare/claude-fable-vs-claude-fable-5-1)
- [Gemini 3.8 Flash vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-gemini-3-8-flash)
- [Claude Fable 5 vs Gemini 3.8 Flash Cyber](/compare/claude-fable-vs-gemini-3-8-flash-cyber)
- [Gemini 3.8 Flash vs Gemini 3.8 Flash Cyber](/compare/gemini-3-8-flash-vs-gemini-3-8-flash-cyber)

## Explore More

- [Claude Fable 5 profile](/models/claude-fable)
- [Gemini 3.8 Flash profile](/models/gemini-3-8-flash)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)