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Claude Fable 5.1 vs Seed 2.1 Pro

Claude Fable 5.1 leads the LLM Stats Score 57.0 to 46.6.

Anthropic · ByteDance · Updated for 2026

Which is better?

Claude Fable 5.1 leads the overall LLM Stats Score 57.0 to 46.6, ranking #1 overall.

In the 1 individual benchmarks reported for both models, Claude Fable 5.1 wins 1; 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 Fable 5.1

  • overall performance matters — it scores 57.0 and ranks #1 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you value its reported benchmark strengths — it wins 1 of 1 exact shared results
  • you want the most recent training data — it shipped Sep 2026

Choose Seed 2.1 Pro

  • you are already invested in the ByteDance ecosystem

At a glance

The differences that matter most.

Claude Fable 5.1
Anthropic
Seed 2.1 Pro
ByteDance
Core performance indexes
LLM Stats Score
57.0
#1
46.6
#24
Reasoning
54.5
#4
47.5
#21
Coding
37.0
#17
33.8
#30
Agents
42.2
#1
31.6
#25
Cost, coverage & limits
Benchmark wins
1 of 1
0 of 1
Input price
$10.00 / M
— / M
Output price
$50.00 / M
— / M
Context window
1,000,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Claude Fable 5.1
Seed 2.1 Pro
Vision
40.8#1
34.2#11
Tool use
31.6#8
26.5#26
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

7 reported for Claude Fable 5.1 · 94 for Seed 2.1 Pro

1 shared

Claude Fable 5.1 outperforms in 1 benchmarks (Humanity's Last Exam), while Seed 2.1 Pro is better at 0 benchmarks.

Claude Fable 5.1 significantly outperforms across most benchmarks.

Thu Sep 03 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 Fable 5.1 specifies input context (1,000,000 tokens). Only Claude Fable 5.1 specifies output context (128,000 tokens).

Anthropic
Claude Fable 5.1
Input1,000,000 tokens
Output128,000 tokens
ByteDance
Seed 2.1 Pro
Input- tokens
Output- tokens
Thu Sep 03 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Claude Fable 5.1 and Seed 2.1 Pro support multimodal inputs.

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

Claude Fable 5.1

Text
Images
Audio
Video

Seed 2.1 Pro

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 Fable 5.1

Proprietary

Closed source

Seed 2.1 Pro

Proprietary

Closed source

Release Timeline

When each model was launched

Claude Fable 5.1 was released on 2026-09-01, while Seed 2.1 Pro was released on 2026-06-24.

Claude Fable 5.1 is 2 months newer than Seed 2.1 Pro.

Claude Fable 5.1

Sep 1, 2026

1 days ago

2mo newer
Seed 2.1 Pro

Jun 24, 2026

2 months ago

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Claude Fable 5.1 and Seed 2.1 Pro side-by-side, then vote on the output you prefer.

Claude Fable 5.1
✓ Preferred
Seed 2.1 Pro
Open in Playground

FAQ

Common questions about Claude Fable 5.1 vs Seed 2.1 Pro.

Which is better, Claude Fable 5.1 or Seed 2.1 Pro?

Claude Fable 5.1 leads the LLM Stats Score 57.0 to 46.6. Claude Fable 5.1 is made by Anthropic and Seed 2.1 Pro 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 Fable 5.1 compare to Seed 2.1 Pro in benchmarks?

Claude Fable 5.1 scores OSWorld 2.0: 77.9%, CursorBench v3.2: 73.4%, Humanity's Last Exam: 65.0%, GDPval-AA: 61.8%, Terminal-Bench 4.0: 55.8%. Seed 2.1 Pro scores CharXiv-D: 95.5%, MathVision: 94.5%, MathVista: 90.7%, MathVerse: 89.7%, Video-MME: 89.2%.

What are the context window sizes for Claude Fable 5.1 and Seed 2.1 Pro?

Claude Fable 5.1 supports 1.0M tokens and Seed 2.1 Pro 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 Fable 5.1 and Seed 2.1 Pro?

Key differences include LLM Stats Score (57.0 vs 46.6). See the full comparison above for benchmark-by-benchmark results.

Who makes Claude Fable 5.1 and Seed 2.1 Pro?

Claude Fable 5.1 is developed by Anthropic and Seed 2.1 Pro is developed by ByteDance.

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