Claude Opus 5.5 (Xhigh, Default Fallback) vs GPT-5.6 Luna (Low)
Which is better for the money: Claude Opus 5.5 (Xhigh, Default Fallback) by Anthropic or GPT-5.6 Luna (Low) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-27.
Trade-off
Verdict
Depends on your budget
Claude Opus 5.5 (Xhigh, Default Fallbac… scores 35.0 points higher (56.0 vs 21.0) but costs 150× as much to run the benchmark ($4057 vs $27.0; flagship vs budget cost classes). They are not alternatives at one budget: pick Claude Opus 5.5 (Xhigh, Default Fallbac… when you need intelligence above 21.0, and GPT-5.6 Luna (Low) when 21.0 is enough.
| Metric | Claude Opus 5.5 (Xhigh, Default Fallback) | GPT-5.6 Luna (Low) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 56.0 | 21.0 | −62.5% GPT-5.6 Luna (Low) is 62.5% less intelligent |
| Total AA cost (lower is better) | $4,056.65 | $27.02 | −99.3% GPT-5.6 Luna (Low) is 99.3% cheaper |
| End-to-end time (lower is better) | 127.76s | 5.68s | −95.6% GPT-5.6 Luna (Low) is 95.6% faster |
| Price per 1M tokens (in / out) | $4.00 / $20.0 | $0.20 / $1.20 | |
| Input modalities | Text, Image | Text, Image |
GPT-5.6 Luna (Low) vs Claude Opus 5.5 (Xhigh, Default Fallback): 62.5% less intelligence, 99.3% less cost to run the AA benchmark, and 95.6% faster end-to-end.
Today's Pareto frontier
Against the frontier
- Claude Opus 5.5 (Xhigh, Default Fallback) is on today's frontier: nothing is both smarter and cheaper.
- 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.
Claude Opus 5.5 (Xhigh, Default Fallback)GPT-5.6 Luna (Low)Today's Pareto frontierEvery other model
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Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/claude-opus-5-5-xhigh/gpt-5-6-luna-low · Markdown: /api/v1/compare/claude-opus-5-5-xhigh/gpt-5-6-luna-low?format=md · llms.txt · agent skill