Claude Sonnet 5.5 (Xhigh, Default Fallback) vs GPT-5.6 Luna (Xhigh)
Which is better for the money: Claude Sonnet 5.5 (Xhigh, 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 2026-10-27.
Depends on your budget
Claude Sonnet 5.5 (Xhigh, Default Fallb… scores 17.3 points higher (51.9 vs 34.6) but costs 12× as much to run the benchmark ($2177 vs $179; flagship vs mid-range cost classes). They are not alternatives at one budget: pick Claude Sonnet 5.5 (Xhigh, Default Fallb… when you need intelligence above 34.6, and GPT-5.6 Luna (Xhigh) when 34.6 is enough.
| Metric | Claude Sonnet 5.5 (Xhigh, Default Fallback) | GPT-5.6 Luna (Xhigh) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 51.9 | 34.6 | −33.3% GPT-5.6 Luna (Xhigh) is 33.3% less intelligent |
| Total AA cost (lower is better) | $2,176.82 | $179.33 | −91.8% GPT-5.6 Luna (Xhigh) is 91.8% cheaper |
| End-to-end time (lower is better) | 33.80s | 45.86s | +35.7% GPT-5.6 Luna (Xhigh) is 35.7% 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 (Xhigh, Default Fallback): 33.3% less intelligence, 91.8% less cost to run the AA benchmark, and 35.7% slower 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 (Xhigh) is off the frontier: at the same or lower cost, GPT-6.1 Terra (Medium) scores 41.30 for $175.
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-xhigh · Markdown: /api/v1/compare/claude-sonnet-5-5-xhigh/gpt-5-6-luna-xhigh?format=md · llms.txt · agent skill