GPT-5.5 Pro vs GLM-5.2

Head-to-head technical comparison of intelligence, capabilities, and API pricing.

GPT-5.5 Pro

OpenAI

AI Mastery Index94.2

LMSYS Arena1468

Technical (MMLU-Pro)94.2%

Cost per 1M Tokens$30

GLM-5.2

Z.ai

AI Mastery Index91.5

LMSYS Arena1465

Technical (MMLU-Pro)91.2%

Cost per 1M Tokens$1.4

Architect's Verdict

When comparing GPT-5.5 Pro and GLM-5.2, GPT-5.5 Pro edges out in overall capabilities according to the AI Mastery Index. However, for cost-sensitive workloads, GLM-5.2 offers a more economical API at $1.4 per 1M tokens. Your choice should depend heavily on whether you prioritize raw reasoning (MMLU) or scalable deployment economics.