GLM-5.1 (Reasoning) vs GPT-5.5 (Xhigh)
Which is better for the money: GLM-5.1 (Reasoning) by Z AI or GPT-5.5 (Xhigh) by OpenAI? 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
GPT-5.5 (Xhigh) scores 12.3 points higher (38.4 vs 26.1) but costs 3.6× as much to run the benchmark ($5294 vs $1487; flagship vs premium cost classes). They are not alternatives at one budget: pick GPT-5.5 (Xhigh) when you need intelligence above 26.1, and GLM-5.1 (Reasoning) when 26.1 is enough.
| Metric | GLM-5.1 (Reasoning) | GPT-5.5 (Xhigh) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 26.1 | 38.4 | +47.1% GPT-5.5 (Xhigh) is 47.1% more intelligent |
| Total AA cost (lower is better) | $1,486.78 | $5,294.36 | +256.1% GPT-5.5 (Xhigh) is 3.6× more expensive |
| End-to-end time (lower is better) | 60.76s | 44.76s | −26.3% GPT-5.5 (Xhigh) is 26.3% faster |
| Price per 1M tokens (in / out) | $1.28 / $4.07 | $5.00 / $30.0 | |
| Input modalities | Text | Text, Image |
GPT-5.5 (Xhigh) vs GLM-5.1 (Reasoning): 47.1% more intelligence, 256.1% more cost to run the AA benchmark, and 26.3% faster end-to-end.
Today's Pareto frontier
Against the frontier
- GLM-5.1 (Reasoning) is off the frontier: at the same or lower cost, GPT-6.1 Sol (Max) scores 51.80 for $1082.
- GPT-5.5 (Xhigh) is off the frontier: at the same or lower cost, Claude Opus 5.5 (Xhigh, Default Fallback) scores 56.00 for $4057.
GLM-5.1 (Reasoning)GPT-5.5 (Xhigh)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/glm-5-1/gpt-5-5 · Markdown: /api/v1/compare/glm-5-1/gpt-5-5?format=md · llms.txt · agent skill