GPT-5.6 Luna vs Seed 2.1 Pro: Specs & Benchmark Comparison
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| Characteristic | GPT-5.6 Luna | Seed 2.1 Pro |
|---|---|---|
| Company | OpenAI | ByteDance |
| Release Date | July 9, 2026 | June 24, 2026 |
| Parameters | — | — |
| Multimodal | Yes | Yes |
| Context (input) | 1.1M | — |
| Context (output) | 128K | — |
| Input Price / 1M | $0.20 | — |
| Output Price / 1M | $1.20 | — |
| Average Score | 0.5 | 0.6 |
| Benchmarks | ||
| DeepSWE | 0.7 | 0.3 |
| Terminal-Bench 2.1 | 0.8 | 0.7 |
| Agents' Last Exam | 0.5 | 0.4 |
| SWE-Bench Pro | 0.6 | 0.6 |
| MMMU-Pro | 0.8 | 0.8 |
| BrowseComp | 0.8 | 0.9 |
| Toolathlon | 0.5 | 0.5 |
Visual Benchmark Comparison
GPT-5.6 Luna
Seed 2.1 Pro
DeepSWE0.7 vs 0.3
0.7
0.3
Terminal-Bench 2.10.8 vs 0.7
0.8
0.7
Agents' Last Exam0.5 vs 0.4
0.5
0.4
SWE-Bench Pro0.6 vs 0.6
0.6
0.6
MMMU-Pro0.8 vs 0.8
0.8
0.8
BrowseComp0.8 vs 0.9
0.8
0.9
Toolathlon0.5 vs 0.5
0.5
0.5
Verdict
GPT-5.6 Luna leads in 1 out of 2 comparison categories.
Overall Performance
Both models show comparable average scores: GPT-5.6 Luna — 0.5, Seed 2.1 Pro — 0.6.
Recency
GPT-5.6 Luna is newer: released 7/9/2026 vs 6/24/2026.
More About These Models
Related Comparisons
Frequently Asked Questions
Which is better for coding — GPT-5.6 Luna or Seed 2.1 Pro?
Direct comparison on the SWE-Bench benchmark is not available. We recommend reviewing other metrics on the comparison page.
Which model is cheaper — GPT-5.6 Luna or Seed 2.1 Pro?
API pricing data is available on the individual model pages.
Which has a larger context window — GPT-5.6 Luna or Seed 2.1 Pro?
Context window data is available on the individual model pages.
The GPT-5.6 Luna and Seed 2.1 Pro comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the GPT-5.6 Luna or Seed 2.1 Pro page. See also the complete list of AI model comparisons.