GLM-5.1 (Reasoning) vs GPT-5.5 (Medium)
Which is better for the money: GLM-5.1 (Reasoning) by Z AI or GPT-5.5 (Medium) 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 (Medium) scores 7.7 points higher (33.8 vs 26.1) but costs 1.4× as much to run the benchmark ($2095 vs $1487; flagship vs premium cost classes). Pick GPT-5.5 (Medium) when the extra intelligence is worth the premium, otherwise GLM-5.1 (Reasoning).
| Metric | GLM-5.1 (Reasoning) | GPT-5.5 (Medium) | Difference |
|---|---|---|---|
| Intelligence (higher is better) | 26.1 | 33.8 | +29.5% GPT-5.5 (Medium) is 29.5% more intelligent |
| Total AA cost (lower is better) | $1,486.78 | $2,095.12 | +40.9% GPT-5.5 (Medium) is 40.9% more expensive |
| End-to-end time (lower is better) | 60.76s | 9.97s | −83.6% GPT-5.5 (Medium) is 83.6% faster |
| Price per 1M tokens (in / out) | $1.28 / $4.07 | $5.00 / $30.0 | |
| Input modalities | Text | Text, Image |
GPT-5.5 (Medium) vs GLM-5.1 (Reasoning): 29.5% more intelligence, 40.9% more cost to run the AA benchmark, and 83.6% 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 (Medium) is off the frontier: at the same or lower cost, GPT-6.1 Sol (Max) scores 51.80 for $1082.
GLM-5.1 (Reasoning)GPT-5.5 (Medium)Today's Pareto frontierOpen-weights frontierEvery other model
Matchup
Compare something else
Agents:
Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/glm-5-1/gpt-5-5-medium · Markdown: /api/v1/compare/glm-5-1/gpt-5-5-medium?format=md · llms.txt · agent skill