Pairwise benchmark snapshot · Aug 16, 2026
This page compares GPT-5.6 Luna (OpenAI) and Seed 2.1 Turbo (ByteDance) using the latest snapshots we have as of Aug 16, 2026. On preference Elo, Seed 2.1 Turbo is ahead by 6 points (1,472 vs 1,466; seed-bootstrap (Aug 16, 2026)). On SWE-bench coding, Seed 2.1 Turbo resolves 63.2% versus 61.8% (seed-bootstrap (Aug 16, 2026)). GPT-5.6 Luna streams faster (188 tok/s) while GPT-5.6 Luna is the cheaper output token ($0.6/1M). GPT-5.6 Luna has the larger context window (1.1M tokens). Every cell below is a dated snapshot from a named public source — we do not invent missing scores, and we do not run SWE-bench ourselves.
OpenAI
GPT-5.6 LunaOpenAI 5.6 fast/cheap tier. Official API $0.20/$1.20 per 1M after the Jul 30 80% Luna cut.
ByteDance
Seed 2.1 TurboByteDance Seed 2.1 Turbo, listed on public model timelines as an Aug 10 2026 API drop.
Instant pairwise benchmark recalculation across 400+ LLMs
Category wins across intelligence, speed, and pricing efficiency.
Preference Elo, Coding proficiency, SWE-bench & LiveBench accuracy
Generation throughput and time to first token responsiveness
Cost per million tokens and max context window length
Each spoke is a skill. Farther from the center is better (0–100th percentile). Tap any dot to inspect details.
6 pts advantage
28 tok/s faster
$1.90/1M cheaper
Simulate monthly production API costs based on published $/1M tokens.
GPT-5.6 Luna is estimated to save $42.50/month ($510/year).
Higher SWE-bench (63.2%).
Lower output list price ($0.6/1M).
Lower TTFT (88 ms).
Larger window (1.1M).
Both accept images. Defaulting to the higher-Elo side (Seed 2.1 Turbo).
| Target Workload | Recommended Pick | Evaluation Rationale |
|---|---|---|
| Repo / coding agents | Seed 2.1 Turbo | Higher SWE-bench (63.2%). |
| High-volume chat | GPT-5.6 Luna | Lower output list price ($0.6/1M). |
| Voice / low-latency UI | GPT-5.6 Luna | Lower TTFT (88 ms). |
| Long-document RAG | GPT-5.6 Luna | Larger window (1.1M). |
| Screenshots / vision | Seed 2.1 Turbo | Both accept images. Defaulting to the higher-Elo side (Seed 2.1 Turbo). |
Listed on public model timelines as an Aug 10 2026 API drop. Preview-quality story, indexable because we have a full snapshot.
Luna is the OpenAI fast/cheap 5.6 SKU after Jul 30. It is not Sol. Sort by price and TTFT, not Elo.
High-volume agents that cannot pay Sol. Compare to Luna before you assume the new cheap SKU wins.
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The real PNG is generated at /compare/gpt-5-6-luna-vs-seed-2-1-turbo/opengraph-image for crawlers.
Verified head-to-head card
