Model Comparison

Seed 2.1 Turbo vs GPT-5.6 LunaWhich is better in 2026?

GPT-5.6 Luna shows notably better performance in the majority of benchmarks.

Verdict: Seed 2.1 Turbo vs GPT-5.6 Luna — which is better?

Seed 2.1 Turbo (by ByteDance) and GPT-5.6 Luna (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

Seed 2.1 Turbo outperforms in 2 benchmarks (BrowseComp, MMMU-Pro), while GPT-5.6 Luna is better at 4 benchmarks (DeepSWE, SWE-Bench Pro, Terminal-Bench 2.1, Toolathlon). GPT-5.6 Luna shows notably better performance in the majority of benchmarks.

Choose Seed 2.1 Turbo if…

  • you are already invested in the ByteDance ecosystem

Choose GPT-5.6 Luna if…

  • you want the strongest raw capability — it leads on 4 of 6 shared benchmarks
  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

6 benchmarks

Seed 2.1 Turbo outperforms in 2 benchmarks (BrowseComp, MMMU-Pro), while GPT-5.6 Luna is better at 4 benchmarks (DeepSWE, SWE-Bench Pro, Terminal-Bench 2.1, Toolathlon).

GPT-5.6 Luna shows notably better performance in the majority of benchmarks.

Fri Jul 17 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only GPT-5.6 Luna specifies input context (1,050,000 tokens). Only GPT-5.6 Luna specifies output context (128,000 tokens).

ByteDance
Seed 2.1 Turbo
Input- tokens
Output- tokens
OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Seed 2.1 Turbo and GPT-5.6 Luna support multimodal inputs.

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

Seed 2.1 Turbo

Text
Images
Audio
Video

GPT-5.6 Luna

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.

Seed 2.1 Turbo

Proprietary

Closed source

GPT-5.6 Luna

Proprietary

Closed source

Release Timeline

When each model was launched

Seed 2.1 Turbo was released on 2026-06-24, while GPT-5.6 Luna was released on 2026-07-09.

GPT-5.6 Luna is 1 month newer than Seed 2.1 Turbo.

Seed 2.1 Turbo

Jun 24, 2026

3 weeks ago

GPT-5.6 Luna

Jul 9, 2026

1 weeks ago

2w newer

Knowledge Cutoff

When training data ends

GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Seed 2.1 Turbo's cutoff date is not specified.

We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without Seed 2.1 Turbo's cutoff date.

Seed 2.1 Turbo

—

GPT-5.6 Luna

Feb 2026

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

ByteDance
Higher BrowseComp score (84.9% vs 83.3%)
Higher MMMU-Pro score (82.2% vs 78.4%)
OpenAI
Larger context window (1,050,000 tokens)
Higher DeepSWE score (67.2% vs 23.0%)
Higher SWE-Bench Pro score (62.7% vs 57.0%)
Higher Terminal-Bench 2.1 score (84.7% vs 67.6%)
Higher Toolathlon score (53.4% vs 49.1%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Seed 2.1 Turbo and GPT-5.6 Luna side-by-side, then vote on the output you prefer.

Seed 2.1 Turbo
✓ Preferred
GPT-5.6 Luna
Open in Playground
AI Model Comparison Table
Feature
ByteDance
Seed 2.1 Turbo
OpenAI
GPT-5.6 Luna

FAQ

Common questions about Seed 2.1 Turbo vs GPT-5.6 Luna.

Which is better, Seed 2.1 Turbo or GPT-5.6 Luna?

GPT-5.6 Luna shows notably better performance in the majority of benchmarks. Seed 2.1 Turbo is made by ByteDance and GPT-5.6 Luna is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Seed 2.1 Turbo compare to GPT-5.6 Luna in benchmarks?

Seed 2.1 Turbo scores CharXiv-D: 94.6%, MathVision: 92.7%, MathVista: 90.5%, MathVerse: 89.2%, Video-MME: 89.0%. GPT-5.6 Luna scores Connectors: 99.9%, HealthBench Consensus: 95.1%, GPQA: 92.3%, Search and Function-Calling: 89.7%, Capture-the-Flag Challenges (Internal): 85.2%.

What are the context window sizes for Seed 2.1 Turbo and GPT-5.6 Luna?

Seed 2.1 Turbo supports an unknown number of tokens and GPT-5.6 Luna supports 1.1M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

Who makes Seed 2.1 Turbo and GPT-5.6 Luna?

Seed 2.1 Turbo is developed by ByteDance and GPT-5.6 Luna is developed by OpenAI.

Related comparisons