Claude Fable 5 (Max, Opus 4.8 Fallback) vs GLM-5.1 (Reasoning)
Which is better for the money: Claude Fable 5 (Max, Opus 4.8 Fallback) by Anthropic or GLM-5.1 (Reasoning) by Z AI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-25.
Trade-off
Verdict
Depends on your budget
Claude Fable 5 (Max, Opus 4.8 Fallback) scores 23.5 points higher (49.6 vs 26.1) but costs 7.5× as much to run the benchmark ($11161 vs $1487; flagship vs premium cost classes). They are not alternatives at one budget: pick Claude Fable 5 (Max, Opus 4.8 Fallback) when you need intelligence above 26.1, and GLM-5.1 (Reasoning) when 26.1 is enough.
| Metric | Claude Fable 5 (Max, Opus 4.8 Fallback) | GLM-5.1 (Reasoning) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 49.6 | 26.1 | −47.4% GLM-5.1 (Reasoning) is 47.4% less intelligent |
| Total AA cost (lower is better) | $11,160.86 | $1,486.78 | −86.7% GLM-5.1 (Reasoning) is 86.7% cheaper |
| End-to-end time (lower is better) | 77.70s | 60.76s | −21.8% GLM-5.1 (Reasoning) is 21.8% faster |
| Price per 1M tokens (in / out) | $10.0 / $50.0 | $1.28 / $4.07 | |
| Input modalities | Text, Image | Text |
GLM-5.1 (Reasoning) vs Claude Fable 5 (Max, Opus 4.8 Fallback): 47.4% less intelligence, 86.7% less cost to run the AA benchmark, and 21.8% 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.
- GLM-5.1 (Reasoning) is off the frontier: at the same or lower cost, GPT-6.1 Sol (Max) scores 51.80 for $1082.
Claude Fable 5 (Max, Opus 4.8 Fallback)GLM-5.1 (Reasoning)Today's Pareto frontierOpen-weights frontierEvery other model
Matchup
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Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/claude-fable-5/glm-5-1 · Markdown: /api/v1/compare/claude-fable-5/glm-5-1?format=md · llms.txt · agent skill