GPT-5.6 Terra (Medium) vs GPT-6 Luna (Medium)
Which is better for the money: GPT-5.6 Terra (Medium) by OpenAI or GPT-6 Luna (Medium) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-24.
Trade-off
Verdict
Depends on your budget
GPT-5.6 Terra (Medium) scores 0.2 points higher (30.1 vs 29.9) but costs 14× as much to run the benchmark ($447 vs $31.2; mid-range vs budget cost classes). They are not alternatives at one budget: pick GPT-5.6 Terra (Medium) when you need intelligence above 29.9, and GPT-6 Luna (Medium) when 29.9 is enough.
| Metric | GPT-5.6 Terra (Medium) | GPT-6 Luna (Medium) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 30.1 | 29.9 | −0.7% GPT-6 Luna (Medium) is 0.7% less intelligent |
| Total AA cost (lower is better) | $446.53 | $31.17 | −93.0% GPT-6 Luna (Medium) is 93.0% cheaper |
| End-to-end time (lower is better) | 5.85s | 8.25s | +41.0% GPT-6 Luna (Medium) is 41.0% slower |
| Price per 1M tokens (in / out) | $2.00 / $12.0 | $0.10 / $0.50 | |
| Input modalities | Text, Image | Text, Image |
GPT-6 Luna (Medium) vs GPT-5.6 Terra (Medium): 0.7% less intelligence, 93.0% less cost to run the AA benchmark, and 41.0% slower end-to-end.
Today's Pareto frontier
Against the frontier
- GPT-5.6 Terra (Medium) is off the frontier: at the same or lower cost, GPT-6.1 Sol (Medium) scores 47.80 for $361.
- GPT-6 Luna (Medium) is on today's frontier: nothing is both smarter and cheaper.
GPT-5.6 Terra (Medium)GPT-6 Luna (Medium)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-5-6-terra-medium/gpt-6-luna-medium · Markdown: /api/v1/compare/gpt-5-6-terra-medium/gpt-6-luna-medium?format=md · llms.txt · agent skill