Claude Sonnet 5.5 (Medium, Default Fallback) vs GPT-5.6 Luna (Xhigh)
Which is better for the money: Claude Sonnet 5.5 (Medium, Default Fallback) by Anthropic or GPT-5.6 Luna (Xhigh) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-26.
Depends on your budget
Claude Sonnet 5.5 (Medium, Default Fall… scores 6.2 points higher (40.8 vs 34.6) but costs 3.5× as much to run the benchmark ($622 vs $179; premium vs mid-range cost classes). They are not alternatives at one budget: pick Claude Sonnet 5.5 (Medium, Default Fall… when you need intelligence above 34.6, and GPT-5.6 Luna (Xhigh) when 34.6 is enough.
| Metric | Claude Sonnet 5.5 (Medium, Default Fallback) | GPT-5.6 Luna (Xhigh) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 40.8 | 34.6 | −15.2% GPT-5.6 Luna (Xhigh) is 15.2% less intelligent |
| Total AA cost (lower is better) | $622.28 | $179.33 | −71.2% GPT-5.6 Luna (Xhigh) is 71.2% cheaper |
| End-to-end time (lower is better) | 6.28s | 40.39s | +543.2% GPT-5.6 Luna (Xhigh) is 543.2% slower |
| Price per 1M tokens (in / out) | $2.00 / $10.0 | $0.20 / $1.20 | |
| Input modalities | Text, Image | Text, Image |
GPT-5.6 Luna (Xhigh) vs Claude Sonnet 5.5 (Medium, Default Fallback): 15.2% less intelligence, 71.2% less cost to run the AA benchmark, and 543.2% slower end-to-end.
Against the frontier
- Claude Sonnet 5.5 (Medium, Default Fallback) is off the frontier: at the same or lower cost, GPT-6.1 Sol (High) scores 50.20 for $521.
- GPT-5.6 Luna (Xhigh) is off the frontier: at the same or lower cost, Claude Haiku 5.5 (Xhigh) scores 41.20 for $158.
Compare something else
Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/claude-sonnet-5-5-medium/gpt-5-6-luna-xhigh · Markdown: /api/v1/compare/claude-sonnet-5-5-medium/gpt-5-6-luna-xhigh?format=md · llms.txt · agent skill