GLM-5.1 vs o4-mini
GLM-5.1 and o4-mini are both current production-tier models. GLM-5.1 is meaningfully cheaper at $1 / $3.2 per 1M. GLM-5.1 leads on multilingual. o4-mini leads on reasoning, instruction following.
Specs side by side
| Metric | Z.ai GLM-5.1 | OpenAI o4-mini |
|---|---|---|
| Input price (per 1M) | $1 | $1.1 |
| Output price (per 1M) | $3.2 | $4.4 |
| Context window | 200k tokens | 200k tokens |
| Speed tier | balanced | slow |
| Open weights | Yes | No |
| EU region | No | Yes |
| Free tier | bigmodel.cn | No |
| Prompt caching | No | Yes |
| Vision input | No | Yes |
| Extended thinking | Yes | Yes |
When to choose each
Choose GLM-5.1 if…
- You need open weights for self-hosting or fine-tuning
- You want a free tier for prototyping
- Multilingual is central to your workload
Choose o4-mini if…
- EU data residency is required
- HIPAA eligibility is required
- You need image input / vision
- Reasoning is central to your workload
- Instruction following is central to your workload
Benchmark delta
GLM-5.1 leads on
- Multilingual
o4-mini leads on
- Reasoning
- Instruction following
FAQ — GLM-5.1 vs o4-mini
GLM-5.1 vs o4-mini — which is better?
GLM-5.1 and o4-mini are both current production-tier models. GLM-5.1 is meaningfully cheaper at $1 / $3.2 per 1M. GLM-5.1 leads on multilingual. o4-mini leads on reasoning, instruction following. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does GLM-5.1 pricing compare to o4-mini?
GLM-5.1 costs $1 / $3.2 per 1M vs o4-mini at $1.1 / $4.4 per 1M. GLM-5.1 is cheaper on output tokens by roughly 38%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does GLM-5.1 or o4-mini have the bigger context window?
o4-mini has a 200k-token context window — 1× the 200k context of GLM-5.1. Enough for long reports and multi-document analysis.
Is there a free tier for GLM-5.1 or o4-mini?
GLM-5.1: yes — Free tier with monthly token allowance. o4-mini: no — Paid-only.
Which is better for coding — GLM-5.1 or o4-mini?
GLM-5.1 leads on coding benchmarks (GLM-5.1: 93/100, o4-mini: 92/100). For production coding agents also weigh tool-use performance — GLM-5.1 scores 86, o4-mini scores 88.