Pairwise benchmark snapshot · Aug 16, 2026
In this head-to-head showdown, GPT-5.6 Luna delivers higher overall intelligence and human-preferred responses (Elo 1,466 vs 1,350), while Gemini 2.5 Pro leads in SWE-bench software engineering benchmarks (63.8%), while GPT-5.6 Luna is more budget-friendly at $1.2/1M per 1M output tokens. Review the complete breakdown below to determine which model best fits your performance and budget requirements.
9 direct benchmark disciplines evaluated across capability, speed, and cost
OpenAI 5.6 fast/cheap tier. Official API $0.20/$1.20 per 1M after the Jul 30 80% Luna cut.
Currently comparing Gemini 2.5 Pro vs GPT-5.6 Luna. Alternative family tiers available.
Δ 116 Arena Elo pts
188 tok/s
$1.2 / 1M output
Relative percentile scores computed across all active models in the benchmark catalog.
Comparing top Western standard models with China's leading frontier rival across 6 skill dimensions. Tap any spoke or dot to inspect.
Category wins across reasoning intelligence, generation speed, and token cost.
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
| Benchmark | Gemini 2.5 Pro | GPT-5.6 Luna | Advantage Delta |
|---|---|---|---|
| Preference Elo | +116 | ||
| Coding Elo | — | — | |
| LiveBench | +7.1% | ||
| SWE-bench | +2% | ||
| GPQA Diamond | +1% | ||
| Time to first token | +122 ms | ||
| Output speed | 95 tok/s | 188 tok/s | +93 tok/s |
| Input price | $1.25/1M | +$1.05/1M | |
| Output price | +$3.8/1M | ||
| Context window | +1M |
Simulate monthly production API costs in USD (US Dollar).
GPT-5.6 Luna is estimated to save $93.75/month ($1,125/year).
Higher SWE-bench (63.8%).
Lower output list price ($1.2/1M).
Lower TTFT (88 ms).
Larger window (2M).
Both accept images. Defaulting to the higher-Elo side (GPT-5.6 Luna).
| Target Workload | Recommended Pick | Evaluation Rationale |
|---|---|---|
| Repo / coding agents | Gemini 2.5 Pro | Higher SWE-bench (63.8%). |
| High-volume chat | GPT-5.6 Luna | Lower output list price ($1.2/1M). |
| Voice / low-latency UI | GPT-5.6 Luna | Lower TTFT (88 ms). |
| Long-document RAG | Gemini 2.5 Pro | Larger window (2M). |
| Screenshots / vision | GPT-5.6 Luna | Both accept images. Defaulting to the higher-Elo side (GPT-5.6 Luna). |
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.
2025-03 row. 3.x Pro replaced it. Kept for old “2.5 pro vs gpt-4o” inbound.
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Verified Head-to-Head Telemetry
