GPT-5.6 Terra (Xhigh) vs GPT-6 Luna (Low)
Which is better for the money: GPT-5.6 Terra (Xhigh) by OpenAI or GPT-6 Luna (Low) 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-5.6 Terra (Xhigh) scores 16.5 points higher (38.0 vs 21.5) but costs 112× as much to run the benchmark ($1187 vs $10.6; premium vs budget cost classes). They are not alternatives at one budget: pick GPT-5.6 Terra (Xhigh) when you need intelligence above 21.5, and GPT-6 Luna (Low) when 21.5 is enough.
| Metric | GPT-5.6 Terra (Xhigh) | GPT-6 Luna (Low) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 38.0 | 21.5 | −43.4% GPT-6 Luna (Low) is 43.4% less intelligent |
| Total AA cost (lower is better) | $1,186.77 | $10.63 | −99.1% GPT-6 Luna (Low) is 99.1% cheaper |
| End-to-end time (lower is better) | 31.98s | 7.07s | −77.9% GPT-6 Luna (Low) is 77.9% faster |
| Price per 1M tokens (in / out) | $2.00 / $12.0 | $0.10 / $0.50 | |
| Input modalities | Text, Image | Text, Image |
GPT-6 Luna (Low) vs GPT-5.6 Terra (Xhigh): 43.4% less intelligence, 99.1% less cost to run the AA benchmark, and 77.9% faster end-to-end.
Today's Pareto frontier
Against the frontier
- GPT-5.6 Terra (Xhigh) is off the frontier: at the same or lower cost, GPT-6.1 Sol (Max) scores 51.80 for $1082.
- GPT-6 Luna (Low) is on today's frontier: nothing is both smarter and cheaper.
GPT-5.6 Terra (Xhigh)GPT-6 Luna (Low)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-5-6-terra-xhigh/gpt-6-luna-low · Markdown: /api/v1/compare/gpt-5-6-terra-xhigh/gpt-6-luna-low?format=md · llms.txt · agent skill