Claude Fable 5 (Max, Opus 4.8 Fallback) vs GPT-5.6 Luna (Xhigh)
Which is better for the money: Claude Fable 5 (Max, Opus 4.8 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.
Trade-off
Verdict
Depends on your budget
Claude Fable 5 (Max, Opus 4.8 Fallback) scores 15.0 points higher (49.6 vs 34.6) but costs 62× as much to run the benchmark ($11161 vs $179; flagship vs mid-range cost classes). They are not alternatives at one budget: pick Claude Fable 5 (Max, Opus 4.8 Fallback) when you need intelligence above 34.6, and GPT-5.6 Luna (Xhigh) when 34.6 is enough.
| Metric | Claude Fable 5 (Max, Opus 4.8 Fallback) | GPT-5.6 Luna (Xhigh) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 49.6 | 34.6 | −30.2% GPT-5.6 Luna (Xhigh) is 30.2% less intelligent |
| Total AA cost (lower is better) | $11,160.86 | $179.33 | −98.4% GPT-5.6 Luna (Xhigh) is 98.4% cheaper |
| End-to-end time (lower is better) | 123.77s | 45.80s | −63.0% GPT-5.6 Luna (Xhigh) is 63.0% faster |
| Price per 1M tokens (in / out) | $10.0 / $50.0 | $0.20 / $1.20 | |
| Input modalities | Text, Image | Text, Image |
GPT-5.6 Luna (Xhigh) vs Claude Fable 5 (Max, Opus 4.8 Fallback): 30.2% less intelligence, 98.4% less cost to run the AA benchmark, and 63.0% faster end-to-end.
Today's Pareto frontier
Against the frontier
- Claude Fable 5 (Max, Opus 4.8 Fallback) is off the frontier: at the same or lower cost, Claude Opus 5.5 (Max, Default Fallback) scores 57.60 for $8708.
- 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.
Claude Fable 5 (Max, Opus 4.8 Fallback)GPT-5.6 Luna (Xhigh)Today's Pareto frontierEvery other model
Matchup
Compare something else
Agents:
Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/claude-fable-5/gpt-5-6-luna-xhigh · Markdown: /api/v1/compare/claude-fable-5/gpt-5-6-luna-xhigh?format=md · llms.txt · agent skill