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Claude Sonnet 5.5 vs Seed 2.1 Turbo

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 43.0.

Anthropic · ByteDance · Updated for 2026

Which is better?

Claude Sonnet 5.5 leads the overall LLM Stats Score 58.0 to 43.0, ranking #3 overall.

In the 3 individual benchmarks reported for both models, Claude Sonnet 5.5 wins 2; this is a narrower head-to-head signal than the composite indexes.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Claude Sonnet 5.5

  • overall performance matters — it scores 58.0 and ranks #3 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 2 of 3 exact shared results
  • you want the most recent training data — it shipped Sep 2026

Choose Seed 2.1 Turbo

  • you are already invested in the ByteDance ecosystem

At a glance

The differences that matter most.

Claude Sonnet 5.5
Anthropic
Seed 2.1 Turbo
ByteDance
Core performance indexes
LLM Stats Score
58.0
#3
43.0
#48
Reasoning
56.6
#3
44.4
#37
Coding
48.8
#2
30.5
#53
Agents
42.3
#3
28.9
#44
Cost, coverage & limits
Benchmark wins
2 of 3
1 of 3
Input price
$2.00 / M
— / M
Output price
$10.00 / M
— / M
Context window
1,000,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

4 shared
Index
Claude Sonnet 5.5
Seed 2.1 Turbo
Math
36.9#34
39.6#18
Vision
40.0#3
30.4#32
Tool use
34.0#2
19.3#61
Multimodal
40.1#2
33.5#17
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

47 reported for Claude Sonnet 5.5 · 90 for Seed 2.1 Turbo

3 shared

Claude Sonnet 5.5 outperforms in 2 benchmarks (Program Bench, SWE-Bench Pro), while Seed 2.1 Turbo is better at 1 benchmark (OfficeQA Pro).

Claude Sonnet 5.5 shows notably better performance in the majority of benchmarks.

Fri Oct 02 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only Claude Sonnet 5.5 specifies input context (1,000,000 tokens). Only Claude Sonnet 5.5 specifies output context (128,000 tokens).

Anthropic
Claude Sonnet 5.5
Input1,000,000 tokens
Output128,000 tokens
ByteDance
Seed 2.1 Turbo
Input- tokens
Output- tokens
Fri Oct 02 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Sonnet 5.5 and Seed 2.1 Turbo support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Claude Sonnet 5.5

Text
Images
Audio
Video

Seed 2.1 Turbo

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Claude Sonnet 5.5

Proprietary

Closed source

Seed 2.1 Turbo

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Sonnet 5.5 was released on 2026-09-28, while Seed 2.1 Turbo was released on 2026-06-24.

Claude Sonnet 5.5 is 3 months newer than Seed 2.1 Turbo.

Claude Sonnet 5.5

Sep 28, 2026

4 days ago

3mo newer
Seed 2.1 Turbo

Jun 24, 2026

3 months ago

Knowledge Cutoff

When training data ends

Claude Sonnet 5.5 has a documented knowledge cutoff of 2026-06-01, while Seed 2.1 Turbo's cutoff date is not specified.

We can confirm Claude Sonnet 5.5's training data extends to 2026-06-01, but cannot make a direct comparison without Seed 2.1 Turbo's cutoff date.

Claude Sonnet 5.5

Jun 2026

Seed 2.1 Turbo

—

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Claude Sonnet 5.5 and Seed 2.1 Turbo side-by-side, then vote on the output you prefer.

Claude Sonnet 5.5
✓ Preferred
Seed 2.1 Turbo
Open in Playground

FAQ

Common questions about Claude Sonnet 5.5 vs Seed 2.1 Turbo.

Which is better, Claude Sonnet 5.5 or Seed 2.1 Turbo?

Claude Sonnet 5.5 leads the LLM Stats Score 58.0 to 43.0. Claude Sonnet 5.5 is made by Anthropic and Seed 2.1 Turbo is made by ByteDance. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Claude Sonnet 5.5 compare to Seed 2.1 Turbo in benchmarks?

Claude Sonnet 5.5 scores BenchCAD (with Python tool): 96.3%, ArXivMath (with tools): 95.2%, Global-MMLU: 92.1%, MILU: 91.6%, SWE-bench Multilingual: 90.3%. Seed 2.1 Turbo scores CharXiv-D: 94.6%, MathVision: 92.7%, MathVista: 90.5%, MathVerse: 89.2%, Video-MME: 89.0%.

What are the context window sizes for Claude Sonnet 5.5 and Seed 2.1 Turbo?

Claude Sonnet 5.5 supports 1.0M tokens and Seed 2.1 Turbo supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Claude Sonnet 5.5 and Seed 2.1 Turbo?

Key differences include LLM Stats Score (58.0 vs 43.0). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Sonnet 5.5 and Seed 2.1 Turbo?

Claude Sonnet 5.5 is developed by Anthropic and Seed 2.1 Turbo is developed by ByteDance.

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