# Claude Fable 5.1 vs Gemini 3.5 Flash

> Side-by-side benchmark comparison for Claude Fable 5.1 and Gemini 3.5 Flash across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-fable-5-1-vs-gemini-3-5-flash
- Last updated: October 17, 2026

- Shared sourced benchmarks: 12
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Pick Claude Fable 5.1 if you want the stronger benchmark profile. Gemini 3.5 Flash only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Claude Fable 5.1 leads overall 83.18 to 61.88.
- The clearest category separation is in mathematics, where the averages are 96.8 for Claude Fable 5.1 and 67.1 for Gemini 3.5 Flash.
- The biggest single benchmark swing is FrontierMath v2 (Tier 4) in Mathematics, with scores of 87.805% and 26.829%.
- Gemini 3.5 Flash is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.

## Model Snapshot

| Property | Claude Fable 5.1 | Gemini 3.5 Flash |
|----------|----------|----------|
| Creator | Anthropic | Google |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 1M |
| Overall Score | 83.18 | 61.88 |
| Benchmarks Covered | 33 | 29 |
| Pricing (input/output) | $10.00 / $50.00 | $1.50 / $9.00 |

## Category Breakdown

### Agentic

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 80.9 (Supported · #2/128)
- Gemini 3.5 Flash public-lane score: 51.3 (Supported · #45/128)

| Benchmark | Claude Fable 5.1 | Gemini 3.5 Flash | 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% | 74.2% | 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 2.1 | Coming soon | 76.2% | Coming soon |
| MCP Atlas | Coming soon | 83.6% | Coming soon |
| Toolathlon | Coming soon | 56.5% | Coming soon |
| OSWorld-Verified | Coming soon | 78.4% | Coming soon |
| Finance Agent v2 | Coming soon | 57.9% | Coming soon |
| Gert Labs | Coming soon | 61.85% | Coming soon |
| ResearchClawBench | Coming soon | 18.0% | Coming soon |

### Coding

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 76.8 (Supported · #3/150)
- Gemini 3.5 Flash public-lane score: 50.1 (Supported · #43/150)

| Benchmark | Claude Fable 5.1 | Gemini 3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| Bug Hunt Bench | 43.0 fixes | Coming soon | Coming soon |
| SWE-bench Pro | 81.2% | 55.1% | 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% | 48.8% | Claude Fable 5.1 |
| LiveCodeBench (Vals) | 90.5% | 87.6% | Claude Fable 5.1 |
| CursorBench 4.0 | 51.8% | Coming soon | Coming soon |
| PostTrainBench v1.1 | 40.2% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 76.2% | Coming soon |
| Vibe Code Bench | Coming soon | 48.68% | Coming soon |
| cursorBench31 | Coming soon | 49.8% | Coming soon |
| SWE-bench (Vals) | Coming soon | 78.8% | Coming soon |

### Reasoning

- Winner: Directional only
- Claude Fable 5.1 public-lane score: 85.2 (#4/28)
- Gemini 3.5 Flash public-lane score: 70.9 (#19/28)

| Benchmark | Claude Fable 5.1 | Gemini 3.5 Flash | 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 |
| MRCRv2 | Coming soon | 77.3% | Coming soon |
| MRCR 1M | Coming soon | 26.6% | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: Coming soon
- Gemini 3.5 Flash public-lane score: 87.8 (#7/54)

| Benchmark | Claude Fable 5.1 | Gemini 3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | Coming soon | 84.2% | Coming soon |
| MMMU-Pro | Coming soon | 83.6% | Coming soon |
| Blueprint-Bench 2 | Coming soon | 33.6% | Coming soon |

### Knowledge

- Winner: Claude Fable 5.1
- Claude Fable 5.1 public-lane score: 86.9 (Supported · #2/184)
- Gemini 3.5 Flash public-lane score: 65.6 (Supported · #32/184)

| Benchmark | Claude Fable 5.1 | Gemini 3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| HLE | 65% | 40.2% | Claude Fable 5.1 |
| HLE w/o tools | 60.9% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 93.4% | 92.7% | Claude Fable 5.1 |
| MMLU-Pro (Vals) | 92.4% | 89.5% | Claude Fable 5.1 |
| GPQA-D | Coming soon | 92.7% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Claude Fable 5.1 public-lane score: Coming soon
- Gemini 3.5 Flash public-lane score: 87.4 (#37/148)

| Benchmark | Claude Fable 5.1 | Gemini 3.5 Flash | 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)
- Gemini 3.5 Flash public-lane score: 67.1 (Unranked · 2 rankable rows)

| Benchmark | Claude Fable 5.1 | Gemini 3.5 Flash | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 90.175% | 62.807% | Claude Fable 5.1 |
| FrontierMath v2 (Tier 4) | 87.805% | 26.829% | Claude Fable 5.1 |

## FAQ

### Which is better overall, Claude Fable 5.1 or Gemini 3.5 Flash?

Claude Fable 5.1 is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Fable 5.1 and Gemini 3.5 Flash?

The widest category gap is in mathematics, where the averages are 96.8 for Claude Fable 5.1 and 67.1 for Gemini 3.5 Flash.

### 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 Gemini 3.5 Flash cover on BenchLM?

Gemini 3.5 Flash currently has 29 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Fable 5.1 vs Claude Fable 5](/compare/claude-fable-vs-claude-fable-5-1)
- [Gemini 3.5 Flash vs Claude Fable 5](/compare/claude-fable-vs-gemini-3-5-flash)
- [Claude Fable 5.1 vs Gemini 3.5 Flash Cyber](/compare/claude-fable-5-1-vs-gemini-3-5-flash-cyber)
- [Gemini 3.5 Flash vs Gemini 3.5 Flash Cyber](/compare/gemini-3-5-flash-vs-gemini-3-5-flash-cyber)

## Explore More

- [Claude Fable 5.1 profile](/models/claude-fable-5-1)
- [Gemini 3.5 Flash profile](/models/gemini-3-5-flash)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)