# Gemini 3.5 Flash vs Seed 2.1 Pro

> Side-by-side benchmark comparison for Gemini 3.5 Flash and Seed 2.1 Pro across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gemini-3-5-flash-vs-seed-2-1-pro
- Last updated: September 10, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Gemini 3.5 Flash and Seed 2.1 Pro share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Seed 2.1 Pro has the lower published output-token price.
- Gemini 3.5 Flash has the larger published context window at 1M.

## Model Snapshot

| Property | Gemini 3.5 Flash | Seed 2.1 Pro |
|----------|----------|----------|
| Creator | Google | ByteDance |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 256K |
| Independent public score (not head-to-head) | 68.14 | null |
| Benchmarks Covered | 27 | 11 |
| Pricing (input/output) | $1.50 / $9.00 | Pricing unavailable / Pricing unavailable |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Gemini 3.5 Flash public-lane score: 51.7 (Supported · #43/152)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Gemini 3.5 Flash | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 76.2% | Coming soon | Coming soon |
| MCP Atlas | 83.6% | Coming soon | Coming soon |
| Toolathlon | 56.5% | Coming soon | Coming soon |
| OSWorld-Verified | 78.4% | Coming soon | Coming soon |
| Finance Agent v2 | 57.9% | Coming soon | Coming soon |
| Gert Labs | 61.85% | Coming soon | Coming soon |
| ResearchClawBench | 18.0% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 74.2% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 71.0% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Gemini 3.5 Flash public-lane score: 57.5 (Supported · #33/151)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Gemini 3.5 Flash | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.0 | 76.2% | Coming soon | Coming soon |
| SWE-bench Pro | 55.1% | Coming soon | Coming soon |
| Vibe Code Bench | 48.68% | Coming soon | Coming soon |
| cursorBench31 | 49.8% | Coming soon | Coming soon |
| cursorBench32 | 48.8% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 87.6% | Coming soon | Coming soon |
| SWE-bench (Vals) | 78.8% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 71.0% | Coming soon |
| NL2Repo | Coming soon | 47% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Gemini 3.5 Flash public-lane score: 86.9 (#6/48)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Gemini 3.5 Flash | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | 84.2% | 85.4% | Seed 2.1 Pro |
| MMMU-Pro | 83.6% | 81.6% | Gemini 3.5 Flash |
| Blueprint-Bench 2 | 33.6% | Coming soon | Coming soon |
| MathVision | Coming soon | 92.6% | Coming soon |
| ZeroBench | Coming soon | 18.0% | Coming soon |
| BabyVision | Coming soon | 73.7% | Coming soon |
| ERQA | Coming soon | 72.0% | Coming soon |
| Video-MME | Coming soon | 89.2% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Gemini 3.5 Flash public-lane score: 59.4 (#16/20)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Gemini 3.5 Flash | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| MRCRv2 | 77.3% | Coming soon | Coming soon |
| MRCR 1M | 26.6% | Coming soon | Coming soon |
| ARC-AGI-2 | 72.1% | Coming soon | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Gemini 3.5 Flash public-lane score: 67.8 (Supported · #19/183)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Gemini 3.5 Flash | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| GPQA-D | 92.7% | Coming soon | Coming soon |
| HLE | 40.2% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 92.7% | Coming soon | Coming soon |
| MMLU-Pro (Vals) | 89.5% | Coming soon | Coming soon |
| SuperGPQA | Coming soon | 70.8% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Gemini 3.5 Flash public-lane score: 86.9 (#36/123)
- Seed 2.1 Pro public-lane score: Coming soon

### Mathematics

- Winner: Insufficient shared evidence
- Gemini 3.5 Flash public-lane score: 55.2 (Unranked · 2 rankable rows)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Gemini 3.5 Flash | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | 38.966% | Coming soon | Coming soon |
| FrontierMath v2 (Tier 4) | 14.583% | Coming soon | Coming soon |

## FAQ

### Is there enough evidence to pick between Gemini 3.5 Flash and Seed 2.1 Pro?

Not yet. The models share only 2 sourced benchmark rows, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [Gemini 3.5 Flash vs Gemini 3.5 Flash Cyber](/compare/gemini-3-5-flash-vs-gemini-3-5-flash-cyber)
- [Seed 2.1 Pro vs Gemini 3.5 Flash Cyber](/compare/gemini-3-5-flash-cyber-vs-seed-2-1-pro)
- [Gemini 3.5 Flash vs Seed 2.1 Turbo](/compare/gemini-3-5-flash-vs-seed-2-1-turbo)
- [Seed 2.1 Pro vs Seed 2.1 Turbo](/compare/seed-2-1-pro-vs-seed-2-1-turbo)

## Explore More

- [Gemini 3.5 Flash profile](/models/gemini-3-5-flash)
- [Seed 2.1 Pro profile](/models/seed-2-1-pro)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)