# Claude Sonnet 5 vs Seed 2.1 Pro

> Side-by-side benchmark comparison for Claude Sonnet 5 and Seed 2.1 Pro across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

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

- Shared sourced benchmarks: 1
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

Evidence is too thin for a benchmark verdict: Claude Sonnet 5 and Seed 2.1 Pro share only 1 sourced benchmark row.

## Summary

- Only 1 shared sourced benchmark row is 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.
- Claude Sonnet 5 has the larger published context window at 1M.

## Model Snapshot

| Property | Claude Sonnet 5 | Seed 2.1 Pro |
|----------|----------|----------|
| Creator | Anthropic | ByteDance |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 1M | 256K |
| Independent public score (not head-to-head) | 69.84 | null |
| Benchmarks Covered | 24 | 11 |
| Pricing (input/output) | $2.00 / $10.00 | Pricing unavailable / Pricing unavailable |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Claude Sonnet 5 public-lane score: 65.8 (Supported · #11/152)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Claude Sonnet 5 | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 3.0 | 14.6% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | 80.4% | Coming soon | Coming soon |
| BrowseComp | 84.7% | Coming soon | Coming soon |
| HLE w/ tools | 57.4% | Coming soon | Coming soon |
| OSWorld-Verified | 81.2% | Coming soon | Coming soon |
| Terminal-Bench 2.1 (Vals) | 74.5% | Coming soon | Coming soon |
| Terminal-Bench 2.1 | Coming soon | 71.0% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Claude Sonnet 5 public-lane score: 64 (Supported · #13/151)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Claude Sonnet 5 | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| SWE-bench Verified | 85.2% | Coming soon | Coming soon |
| SWE-bench Pro | 63.2% | Coming soon | Coming soon |
| SWE Multilingual | 78.3% | Coming soon | Coming soon |
| SWE Multimodal | 28.1% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | 80.4% | Coming soon | Coming soon |
| FrontierCode 1.1 Main | 42.7% | Coming soon | Coming soon |
| cursorBench32 | 61.5% | Coming soon | Coming soon |
| VulcanBench CII v1 | 89.2% | Coming soon | Coming soon |
| LiveCodeBench (Vals) | 82.4% | Coming soon | Coming soon |
| SWE-bench (Vals) | 79.6% | 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
- Claude Sonnet 5 public-lane score: 77.5 (#13/48)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Claude Sonnet 5 | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | 88.3% | 85.4% | Claude Sonnet 5 |
| CharXiv w/o tools | 77% | Coming soon | Coming soon |
| MathVision | Coming soon | 92.6% | Coming soon |
| MMMU-Pro | Coming soon | 81.6% | 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
- Claude Sonnet 5 public-lane score: 77.4 (Unranked · 2 rankable rows)
- Seed 2.1 Pro public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- Claude Sonnet 5 public-lane score: 66.6 (Supported · #20/183)
- Seed 2.1 Pro public-lane score: Coming soon

| Benchmark | Claude Sonnet 5 | Seed 2.1 Pro | Winner |
|-----------|-----------|-----------|--------|
| HLE | 57.4% | Coming soon | Coming soon |
| HLE w/o tools | 43.2% | Coming soon | Coming soon |
| HLE-Verified | 31.0% | Coming soon | Coming soon |
| LABBench2 | 80.1% | Coming soon | Coming soon |
| GPQA Diamond (Vals) | 88.9% | Coming soon | Coming soon |
| MMLU-Pro (Vals) | 87.5% | Coming soon | Coming soon |
| SuperGPQA | Coming soon | 70.8% | Coming soon |

## FAQ

### Is there enough evidence to pick between Claude Sonnet 5 and Seed 2.1 Pro?

Not yet. The models share only 1 sourced benchmark row, 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

- [Claude Sonnet 5 vs Seed 2.1 Turbo](/compare/claude-sonnet-5-vs-seed-2-1-turbo)
- [Seed 2.1 Pro vs Seed 2.1 Turbo](/compare/seed-2-1-pro-vs-seed-2-1-turbo)
- [Claude Sonnet 5 vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-claude-sonnet-5)
- [Seed 2.1 Pro vs Claude Fable 5.1](/compare/claude-fable-5-1-vs-seed-2-1-pro)

## Explore More

- [Claude Sonnet 5 profile](/models/claude-sonnet-5)
- [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)