GPT-5.5 (High) vs GPT-5.6 Luna (Xhigh)
Which is better for the money: GPT-5.5 (High) by OpenAI or GPT-5.6 Luna (Xhigh) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-27.
Trade-off
Verdict
Depends on your budget
GPT-5.5 (High) scores 2.4 points higher (37.0 vs 34.6) but costs 18× as much to run the benchmark ($3181 vs $179; flagship vs mid-range cost classes). They are not alternatives at one budget: pick GPT-5.5 (High) when you need intelligence above 34.6, and GPT-5.6 Luna (Xhigh) when 34.6 is enough.
| Metric | GPT-5.5 (High) | GPT-5.6 Luna (Xhigh) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 37.0 | 34.6 | −6.5% GPT-5.6 Luna (Xhigh) is 6.5% less intelligent |
| Total AA cost (lower is better) | $3,181.05 | $179.33 | −94.4% GPT-5.6 Luna (Xhigh) is 94.4% cheaper |
| End-to-end time (lower is better) | 35.54s | 39.18s | +10.2% GPT-5.6 Luna (Xhigh) is 10.2% slower |
| Price per 1M tokens (in / out) | $5.00 / $30.0 | $0.20 / $1.20 | |
| Input modalities | Text, Image | Text, Image |
GPT-5.6 Luna (Xhigh) vs GPT-5.5 (High): 6.5% less intelligence, 94.4% less cost to run the AA benchmark, and 10.2% slower end-to-end.
Today's Pareto frontier
Against the frontier
- GPT-5.5 (High) is off the frontier: at the same or lower cost, Kimi K3.1 Pro scores 55.10 for $3117.
- GPT-5.6 Luna (Xhigh) is off the frontier: at the same or lower cost, GPT-6.1 Terra (Medium) scores 41.30 for $175.
GPT-5.5 (High)GPT-5.6 Luna (Xhigh)Today's Pareto frontierEvery other model
Matchup
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Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/gpt-5-5-high/gpt-5-6-luna-xhigh · Markdown: /api/v1/compare/gpt-5-5-high/gpt-5-6-luna-xhigh?format=md · llms.txt · agent skill