GLM-5.2 vs GPT-5.5 Pro
GLM-5.2 and GPT-5.5 Pro are both current production-tier models. GLM-5.2 is meaningfully cheaper at $1.4 / $4.4 per 1M. GLM-5.2 has a 1M context window — about 3× the 400k of GPT-5.5 Pro. GPT-5.5 Pro leads on reasoning, general knowledge, instruction following.
Specs side by side
| Metric | Z.ai GLM-5.2 | OpenAI GPT-5.5 Pro |
|---|---|---|
| Input price (per 1M) | $1.4 | $30 |
| Output price (per 1M) | $4.4 | $180 |
| Context window | 1M tokens | 400k tokens |
| Speed tier | balanced | slow |
| Open weights | Yes | No |
| EU region | No | No |
| Free tier | bigmodel.cn | No |
| Prompt caching | Yes | Yes |
| Vision input | No | Yes |
| Extended thinking | Yes | Yes |
When to choose each
Choose GLM-5.2 if…
- Cost is a priority ($1.4 / $4.4 per 1M vs $30 / $180 per 1M)
- You need 1M context (3× more than GPT-5.5 Pro)
- You need open weights for self-hosting or fine-tuning
- You want a free tier for prototyping
Choose GPT-5.5 Pro if…
- HIPAA eligibility is required
- You need image input / vision
- Reasoning is central to your workload
- General knowledge is central to your workload
Benchmark delta
GLM-5.2 leads on
GLM-5.2 has no meaningful benchmark lead in this pair.
GPT-5.5 Pro leads on
- Reasoning
- General knowledge
- Instruction following
- Tool use
FAQ — GLM-5.2 vs GPT-5.5 Pro
GLM-5.2 vs GPT-5.5 Pro — which is better?
GLM-5.2 and GPT-5.5 Pro are both current production-tier models. GLM-5.2 is meaningfully cheaper at $1.4 / $4.4 per 1M. GLM-5.2 has a 1M context window — about 3× the 400k of GPT-5.5 Pro. GPT-5.5 Pro leads on reasoning, general knowledge, instruction following. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does GLM-5.2 pricing compare to GPT-5.5 Pro?
GLM-5.2 costs $1.4 / $4.4 per 1M vs GPT-5.5 Pro at $30 / $180 per 1M. GLM-5.2 is cheaper on output tokens by roughly 3991%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does GLM-5.2 or GPT-5.5 Pro have the bigger context window?
GLM-5.2 has a 1M-token context window — 3× the 400k context of GPT-5.5 Pro. Enough for entire codebases, books, or multi-document RAG.
Is there a free tier for GLM-5.2 or GPT-5.5 Pro?
GLM-5.2: yes — Free tier with monthly token allowance. GPT-5.5 Pro: no — Paid-only — no free tier.
Which is better for coding — GLM-5.2 or GPT-5.5 Pro?
GPT-5.5 Pro leads on coding benchmarks (GLM-5.2: 93/100, GPT-5.5 Pro: 96/100). For production coding agents also weigh tool-use performance — GLM-5.2 scores 86, GPT-5.5 Pro scores 94.