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Mercury 3 vs Seed 2.1 Pro

Seed 2.1 Pro leads the LLM Stats Score 45.7 to 36.1.

Inception · ByteDance · Updated for 2026

Which is better?

Seed 2.1 Pro leads the overall LLM Stats Score 45.7 to 36.1, ranking #40 overall.

In the 1 individual benchmarks reported for both models, Mercury 3 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 Mercury 3

  • you value its reported benchmark strengths — it wins 1 of 1 exact shared results
  • you want the most recent training data — it shipped Oct 2026

Choose Seed 2.1 Pro

  • overall performance matters — it scores 45.7 and ranks #40 on LLM Stats
  • your work emphasizes reasoning and agents — it leads those capability indexes

At a glance

The differences that matter most.

Mercury 3
Inception
Seed 2.1 Pro
ByteDance
Core performance indexes
LLM Stats Score
36.1
#98
45.7
#40
Reasoning
34.8
#103
47.2
#26
Coding
21.5
#105
32.0
#49
Agents
19.4
#84
31.0
#42
Cost, coverage & limits
Benchmark wins
1 of 1
0 of 1
Input price
$0.10 / M
— / M
Output price
$0.35 / M
— / M
Context window
1,000,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

1 shared
Index
Mercury 3
Seed 2.1 Pro
Long context
23.0#18
29.0#6
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

12 reported for Mercury 3 · 94 for Seed 2.1 Pro

1 shared

Mercury 3 outperforms in 1 benchmarks (SWE-Atlas), while Seed 2.1 Pro is better at 0 benchmarks.

Mercury 3 significantly outperforms across most benchmarks.

Sat Oct 24 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only Mercury 3 specifies input context (1,000,000 tokens). Only Mercury 3 specifies output context (131,072 tokens).

Inception
Mercury 3
Input1,000,000 tokens
Output131,072 tokens
ByteDance
Seed 2.1 Pro
Input- tokens
Output- tokens
Sat Oct 24 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Seed 2.1 Pro supports multimodal inputs, whereas Mercury 3 does not.

Seed 2.1 Pro can handle both text and other forms of data like images, making it suitable for multimodal applications.

Mercury 3

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.

Mercury 3

Proprietary

Closed source

Seed 2.1 Pro

Proprietary

Closed source

Release Timeline

When each model was launched

Mercury 3 was released on 2026-10-19, while Seed 2.1 Pro was released on 2026-06-24.

Mercury 3 is 4 months newer than Seed 2.1 Pro.

Mercury 3

Oct 19, 2026

0 days ago

3mo newer
Seed 2.1 Pro

Jun 24, 2026

3 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?

Judge for yourself.

Run your own prompts against Mercury 3 and Seed 2.1 Pro side-by-side, then vote on the output you prefer.

Mercury 3
✓ Preferred
Seed 2.1 Pro
Open in Playground

FAQ

Common questions about Mercury 3 vs Seed 2.1 Pro.

Which is better, Mercury 3 or Seed 2.1 Pro?

Seed 2.1 Pro leads the LLM Stats Score 45.7 to 36.1. Mercury 3 is made by Inception 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 Mercury 3 compare to Seed 2.1 Pro in benchmarks?

Mercury 3 scores GPQA: 89.2%, AA-LCR: 77.7%, IFBench: 76.8%, MRCR v2: 75.5%, DeepSearchQA: 71.3%. 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 Mercury 3 and Seed 2.1 Pro?

Mercury 3 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 Mercury 3 and Seed 2.1 Pro?

Key differences include LLM Stats Score (36.1 vs 45.7), multimodal support (no vs yes). See the full comparison above for benchmark-by-benchmark results.

Who makes Mercury 3 and Seed 2.1 Pro?

Mercury 3 is developed by Inception and Seed 2.1 Pro is developed by ByteDance.

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