Claude Sonnet 5.5 (Xhigh, Default Fallback) vs GPT-5.6 Luna (Medium)
Which is better for the money: Claude Sonnet 5.5 (Xhigh, Default Fallback) by Anthropic or GPT-5.6 Luna (Medium) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-27.
Depends on your budget
Claude Sonnet 5.5 (Xhigh, Default Fallb… scores 26.9 points higher (51.9 vs 25.0) but costs 49× as much to run the benchmark ($2177 vs $44.3; flagship vs budget cost classes). They are not alternatives at one budget: pick Claude Sonnet 5.5 (Xhigh, Default Fallb… when you need intelligence above 25.0, and GPT-5.6 Luna (Medium) when 25.0 is enough.
| Metric | Claude Sonnet 5.5 (Xhigh, Default Fallback) | GPT-5.6 Luna (Medium) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 51.9 | 25.0 | −51.8% GPT-5.6 Luna (Medium) is 51.8% less intelligent |
| Total AA cost (lower is better) | $2,176.82 | $44.32 | −98.0% GPT-5.6 Luna (Medium) is 98.0% cheaper |
| End-to-end time (lower is better) | 34.85s | 6.68s | −80.8% GPT-5.6 Luna (Medium) is 80.8% faster |
| Price per 1M tokens (in / out) | $2.00 / $10.0 | $0.20 / $1.20 | |
| Input modalities | Text, Image | Text, Image |
GPT-5.6 Luna (Medium) vs Claude Sonnet 5.5 (Xhigh, Default Fallback): 51.8% less intelligence, 98.0% less cost to run the AA benchmark, and 80.8% faster end-to-end.
Against the frontier
- Claude Sonnet 5.5 (Xhigh, Default Fallback) is off the frontier: at the same or lower cost, Claude Opus 5.5 (High, Default Fallback) scores 53.60 for $2172.
- 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.
Compare something else
Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/claude-sonnet-5-5-xhigh/gpt-5-6-luna-medium · Markdown: /api/v1/compare/claude-sonnet-5-5-xhigh/gpt-5-6-luna-medium?format=md · llms.txt · agent skill