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Qwen3.8 Flash vs Seed 2.1 Pro

Qwen3.8 Flash and Seed 2.1 Pro are closely matched at 49.4 and 46.6 on the LLM Stats Score.

Alibaba Cloud / Qwen Team · ByteDance · Updated for 2026

Which is better?

Qwen3.8 Flash and Seed 2.1 Pro are closely matched on the overall LLM Stats Score at 49.4 and 46.6.

In the 11 individual benchmarks reported for both models, Qwen3.8 Flash wins 9; 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 Qwen3.8 Flash

  • you value its reported benchmark strengths — it wins 9 of 11 exact shared results
  • you want the most recent training data — it shipped Aug 2026

Choose Seed 2.1 Pro

  • you are already invested in the ByteDance ecosystem

At a glance

The differences that matter most.

Qwen3.8 Flash
Alibaba Cloud / Qwen Team
Seed 2.1 Pro
ByteDance
Core performance indexes
LLM Stats Score
49.4
#19
46.6
#24
Reasoning
49.1
#18
47.5
#21
Coding
36.1
#22
33.8
#30
Agents
35.0
#18
31.6
#25
Cost, coverage & limits
Benchmark wins
9 of 11
2 of 11
Input price
$0.15 / M
— / M
Output price
$0.47 / M
— / M
Context window
1,000,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

4 shared
Index
Qwen3.8 Flash
Seed 2.1 Pro
Math
32.5#56
39.2#20
Vision
33.9#14
34.2#11
Tool use
30.9#12
26.5#26
Multimodal
35.7#9
37.5#3
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

22 reported for Qwen3.8 Flash · 94 for Seed 2.1 Pro

11 shared

Qwen3.8 Flash outperforms in 9 benchmarks (Agents' Last Exam, CharXiv-R, ClawEval-MM, ERQA, MathVision, NL2Repo, RealWorldQA, SWE-Bench Pro, Toolathlon), while Seed 2.1 Pro is better at 2 benchmarks (Humanity's Last Exam, LVBench).

Qwen3.8 Flash 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 Qwen3.8 Flash specifies input context (1,000,000 tokens). Only Qwen3.8 Flash specifies output context (131,072 tokens).

Alibaba Cloud / Qwen Team
Qwen3.8 Flash
Input1,000,000 tokens
Output131,072 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 Qwen3.8 Flash and Seed 2.1 Pro support multimodal inputs.

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

Qwen3.8 Flash

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.

Qwen3.8 Flash

Proprietary

Closed source

Seed 2.1 Pro

Proprietary

Closed source

Release Timeline

When each model was launched

Qwen3.8 Flash was released on 2026-08-26, while Seed 2.1 Pro was released on 2026-06-24.

Qwen3.8 Flash is 2 months newer than Seed 2.1 Pro.

Qwen3.8 Flash

Aug 26, 2026

1 weeks 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 Qwen3.8 Flash and Seed 2.1 Pro side-by-side, then vote on the output you prefer.

Qwen3.8 Flash
✓ Preferred
Seed 2.1 Pro
Open in Playground

FAQ

Common questions about Qwen3.8 Flash vs Seed 2.1 Pro.

Which is better, Qwen3.8 Flash or Seed 2.1 Pro?

Qwen3.8 Flash and Seed 2.1 Pro are closely matched on the LLM Stats Score at 49.4 and 46.6. Qwen3.8 Flash is made by Alibaba Cloud / Qwen Team 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 Qwen3.8 Flash compare to Seed 2.1 Pro in benchmarks?

Qwen3.8 Flash scores MathVision: 95.7%, LiveCodeBench v6: 91.9%, GPQA: 91.7%, CharXiv-R: 90.6%, RealWorldQA: 88.5%. 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 Qwen3.8 Flash and Seed 2.1 Pro?

Qwen3.8 Flash 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 Qwen3.8 Flash and Seed 2.1 Pro?

Key differences include LLM Stats Score (49.4 vs 46.6). See the full comparison above for benchmark-by-benchmark results.

Who makes Qwen3.8 Flash and Seed 2.1 Pro?

Qwen3.8 Flash is developed by Alibaba Cloud / Qwen Team and Seed 2.1 Pro is developed by ByteDance.

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