GPT-5.5 (Medium) vs GPT-5.6 Luna (Low)
Which is better for the money: GPT-5.5 (Medium) by OpenAI or GPT-5.6 Luna (Low) 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 (Medium) scores 12.8 points higher (33.8 vs 21.0) but costs 78× as much to run the benchmark ($2095 vs $27.0; flagship vs budget cost classes). They are not alternatives at one budget: pick GPT-5.5 (Medium) when you need intelligence above 21.0, and GPT-5.6 Luna (Low) when 21.0 is enough.
| Metric | GPT-5.5 (Medium) | GPT-5.6 Luna (Low) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 33.8 | 21.0 | −37.9% GPT-5.6 Luna (Low) is 37.9% less intelligent |
| Total AA cost (lower is better) | $2,095.12 | $27.02 | −98.7% GPT-5.6 Luna (Low) is 98.7% cheaper |
| End-to-end time (lower is better) | 13.28s | 5.90s | −55.6% GPT-5.6 Luna (Low) is 55.6% 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 (Low) vs GPT-5.5 (Medium): 37.9% less intelligence, 98.7% less cost to run the AA benchmark, and 55.6% faster end-to-end.
Today's Pareto frontier
Against the frontier
- GPT-5.5 (Medium) is off the frontier: at the same or lower cost, GPT-6.1 Sol (Max) scores 51.80 for $1082.
- GPT-5.6 Luna (Low) is off the frontier: at the same or lower cost, GPT-6 Luna (Low) scores 21.50 for $10.6.
GPT-5.5 (Medium)GPT-5.6 Luna (Low)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-medium/gpt-5-6-luna-low · Markdown: /api/v1/compare/gpt-5-5-medium/gpt-5-6-luna-low?format=md · llms.txt · agent skill