GPT-5.5 (High) vs GPT-5.6 Luna (Medium)
Which is better for the money: GPT-5.5 (High) by OpenAI or GPT-5.6 Luna (Medium) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-26.
Trade-off
Verdict
Depends on your budget
GPT-5.5 (High) scores 12.0 points higher (37.0 vs 25.0) but costs 77× as much to run the benchmark ($3411 vs $44.3; flagship vs budget cost classes). They are not alternatives at one budget: pick GPT-5.5 (High) when you need intelligence above 25.0, and GPT-5.6 Luna (Medium) when 25.0 is enough.
| Metric | GPT-5.5 (High) | GPT-5.6 Luna (Medium) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 37.0 | 25.0 | −32.4% GPT-5.6 Luna (Medium) is 32.4% less intelligent |
| Total AA cost (lower is better) | $3,410.76 | $44.32 | −98.7% GPT-5.6 Luna (Medium) is 98.7% cheaper |
| End-to-end time (lower is better) | 36.31s | 6.50s | −82.1% GPT-5.6 Luna (Medium) is 82.1% faster |
| Price per 1M tokens (in / out) | $5.00 / $30.0 | $0.20 / $1.20 | |
| Input modalities | Text, Image | Text, Image |
GPT-5.6 Luna (Medium) vs GPT-5.5 (High): 32.4% less intelligence, 98.7% less cost to run the AA benchmark, and 82.1% faster 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 (Medium) is off the frontier: at the same or lower cost, GPT-6 Luna (Medium) scores 29.90 for $31.2.
GPT-5.5 (High)GPT-5.6 Luna (Medium)Today's Pareto frontierEvery other model
Matchup
Compare something else
Agents:
Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/gpt-5-5-high/gpt-5-6-luna-medium · Markdown: /api/v1/compare/gpt-5-5-high/gpt-5-6-luna-medium?format=md · llms.txt · agent skill