Pairwise benchmark snapshot · Aug 17, 2026
In this head-to-head showdown, GPT-5.6 Luna delivers higher overall intelligence and human-preferred responses (Elo 1,466 vs 1,455), while Claude Sonnet 4 leads in SWE-bench software engineering benchmarks (62.8%), while GPT-5.6 Luna is more budget-friendly at $0.6/1M per 1M output tokens. Review the complete breakdown below to determine which model best fits your performance and budget requirements.
First Sonnet 4 generation. Bridge between 3.5/3.7 and Sonnet 5.
OpenAI 5.6 fast/cheap tier. Official API $0.20/$1.20 per 1M after the Jul 30 80% Luna cut.
Δ 11 Arena Elo pts
188 tok/s
$0.6 / 1M output
Relative percentile scores computed across all active models in the benchmark catalog.
Each spoke is a skill. Farther from the center is better (0–100th percentile). Tap any dot to inspect details.
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 | Claude Sonnet 4 | GPT-5.6 Luna | Advantage Delta |
|---|---|---|---|
| Preference Elo | GPT-5.6 Luna (+11) | ||
| Coding Elo | Claude Sonnet 4 (+10) | ||
| LiveBench | GPT-5.6 Luna (+1%) | ||
| SWE-bench | Claude Sonnet 4 (+1%) | ||
| GPQA Diamond | Claude Sonnet 4 (+1%) | ||
| Time to first token | GPT-5.6 Luna (+132 ms) | ||
| Output speed | 92 tok/s | 188 tok/s | GPT-5.6 Luna (+96 tok/s) |
| Input price | $0.1/1M | GPT-5.6 Luna (+$2.9/1M) | |
| Output price | $0.6/1M | GPT-5.6 Luna (+$14.4/1M) | |
| Context window | GPT-5.6 Luna (+50k) |
Simulate monthly production API costs in USD (US Dollar).
GPT-5.6 Luna is estimated to save $317.50/month ($3,810/year).
Higher SWE-bench (62.8%).
Lower output list price ($0.6/1M).
Lower TTFT (88 ms).
Larger window (1.1M).
Both accept images. Defaulting to the higher-Elo side (GPT-5.6 Luna).
| Target Workload | Recommended Pick | Evaluation Rationale |
|---|---|---|
| Repo / coding agents | Claude Sonnet 4 | Higher SWE-bench (62.8%). |
| 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 | 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.
No comments posted on this matchup yet. Be the first to share an evaluation note!
The real PNG is generated at /compare/claude-sonnet-4-vs-gpt-5-6-luna/opengraph-image for crawlers.
Verified head-to-head card
