# Claude Sonnet 4.5 vs Gemini 3 Flash

> Side-by-side benchmark comparison for Claude Sonnet 4.5 and Gemini 3 Flash across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/claude-sonnet-4-5-vs-gemini-3-flash
- Last updated: September 29, 2026

- Shared sourced benchmarks: 4
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Pick Gemini 3 Flash if you want the stronger benchmark profile. Claude Sonnet 4.5 only makes more sense when its price, context window, or workload-specific category wins matter more than the overall score.

## Summary

- Gemini 3 Flash leads overall 55.5 to 47.85.
- The clearest category separation is in reasoning, where the averages are 19.2 for Claude Sonnet 4.5 and 60.3 for Gemini 3 Flash.
- The biggest single benchmark swing is FrontierMath v2 (Tiers 1-3) in Mathematics, with scores of 13.495% and 35.640%.
- Gemini 3 Flash is the cheaper option on output tokens, which matters if you expect large responses or heavy interactive use.
- Gemini 3 Flash also has the larger context window at 1M.

## Model Snapshot

| Property | Claude Sonnet 4.5 | Gemini 3 Flash |
|----------|----------|----------|
| Creator | Anthropic | Google |
| Type | Proprietary | Proprietary |
| Reasoning | Non-Reasoning | Non-Reasoning |
| Context | 200K | 1M |
| Overall Score | 47.85 | 55.5 |
| Benchmarks Covered | 11 | 11 |
| Pricing (input/output) | $3.00 / $15.00 | $0.50 / $3.00 |

## Category Breakdown

### Agentic

- Winner: Directional only
- Claude Sonnet 4.5 public-lane score: 34.6 (Estimated · #67/117)
- Gemini 3 Flash public-lane score: 31.7 (Supported · #76/117)

| Benchmark | Claude Sonnet 4.5 | Gemini 3 Flash | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 50% | Coming soon | Coming soon |
| OSWorld-Verified | 61.4% | Coming soon | Coming soon |
| VITA-Bench | 17.0% | Coming soon | Coming soon |
| Gert Labs | 48.51% | 56.63% | Gemini 3 Flash |
| JobBench | 27.7% | 11.4% | Claude Sonnet 4.5 |
| Claw-Eval | Coming soon | 49.2% | Coming soon |
| Terminal-Bench 2.1 (Vals) | Coming soon | 53.9% | Coming soon |

### Coding

- Winner: Not comparable
- Claude Sonnet 4.5 public-lane score: Coming soon
- Gemini 3 Flash public-lane score: 36.4 (Supported · #74/143)

| Benchmark | Claude Sonnet 4.5 | Gemini 3 Flash | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 77.2% | Coming soon | Coming soon |
| Vibe Code Bench | Coming soon | 20.20% | Coming soon |
| LiveCodeBench (Vals) | Coming soon | 85.6% | Coming soon |
| SWE-bench (Vals) | Coming soon | 75.0% | Coming soon |

### Reasoning

- Winner: Not comparable
- Claude Sonnet 4.5 public-lane score: 19.2 (Unranked · 1 rankable row)
- Gemini 3 Flash public-lane score: 60.3 (Unranked · 2 rankable rows)

| Benchmark | Claude Sonnet 4.5 | Gemini 3 Flash | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | 13.6% | Coming soon | Coming soon |

### Multimodal & Grounded

- Winner: Not comparable
- Claude Sonnet 4.5 public-lane score: Coming soon
- Gemini 3 Flash public-lane score: 76.9 (Unranked · 1 rankable row)

### Knowledge

- Winner: Not comparable
- Claude Sonnet 4.5 public-lane score: Coming soon
- Gemini 3 Flash public-lane score: 54.3 (Supported · #47/169)

| Benchmark | Claude Sonnet 4.5 | Gemini 3 Flash | Winner |
|-----------|-----------|-----------|--------|
| GPQA | 83.4% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 87.9% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 88.6% | Coming soon |

### Instruction Following

- Winner: Not comparable
- Claude Sonnet 4.5 public-lane score: Coming soon
- Gemini 3 Flash public-lane score: 64.7 (#70/124)

### Mathematics

- Winner: Not comparable
- Claude Sonnet 4.5 public-lane score: 34.6 (Unranked · 2 rankable rows)
- Gemini 3 Flash public-lane score: 50 (Unranked · 2 rankable rows)

| Benchmark | Claude Sonnet 4.5 | Gemini 3 Flash | Winner |
|-----------|-----------|-----------|--------|
| AIME 2025 | 87% | Coming soon | Coming soon |
| FrontierMath v2 (Tiers 1-3) | 13.495% | 35.640% | Gemini 3 Flash |
| FrontierMath v2 (Tier 4) | 4.167% | 4.167% | Tie |

## FAQ

### Which is better overall, Claude Sonnet 4.5 or Gemini 3 Flash?

Gemini 3 Flash is ahead overall on BenchLM right now.

### Where is the biggest gap between Claude Sonnet 4.5 and Gemini 3 Flash?

The widest category gap is in reasoning, where the averages are 19.2 for Claude Sonnet 4.5 and 60.3 for Gemini 3 Flash.

### How many benchmarks does Claude Sonnet 4.5 cover on BenchLM?

Claude Sonnet 4.5 currently has 11 sourced benchmark scores on BenchLM.

### How many benchmarks does Gemini 3 Flash cover on BenchLM?

Gemini 3 Flash currently has 11 sourced benchmark scores on BenchLM.

## Related Comparisons

- [Claude Sonnet 4.5 vs Claude Sonnet 4.5 Thinking](/compare/claude-sonnet-4-5-vs-claude-sonnet-4-5-thinking)
- [Gemini 3 Flash vs Claude Sonnet 4.5 Thinking](/compare/claude-sonnet-4-5-thinking-vs-gemini-3-flash)
- [Claude Sonnet 4.5 vs GPT-6 Astra](/compare/claude-sonnet-4-5-vs-gpt-6-astra)
- [Gemini 3 Flash vs GPT-6 Astra](/compare/gemini-3-flash-vs-gpt-6-astra)

## Explore More

- [Claude Sonnet 4.5 profile](/models/claude-sonnet-4-5)
- [Gemini 3 Flash profile](/models/gemini-3-flash)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)