Gemini 3.1 Pro vs GLM-5.1
Gemini 3.1 Pro and GLM-5.1 are both current production-tier models. GLM-5.1 is meaningfully cheaper at $1 / $3.2 per 1M. Gemini 3.1 Pro has a 2M context window — about 10× the 200k of GLM-5.1. Gemini 3.1 Pro leads on general knowledge, long-context retrieval, instruction following.
Specs side by side
| Metric | Google Gemini 3.1 Pro | Z.ai GLM-5.1 |
|---|---|---|
| Input price (per 1M) | $2 | $1 |
| Output price (per 1M) | $12 | $3.2 |
| Context window | 2M tokens | 200k tokens |
| Speed tier | balanced | balanced |
| Open weights | No | Yes |
| EU region | Yes | No |
| Free tier | No | bigmodel.cn |
| Prompt caching | Yes | No |
| Vision input | Yes | No |
| Extended thinking | Yes | Yes |
When to choose each
Choose Gemini 3.1 Pro if…
- You need 2M context (10× more than GLM-5.1)
- EU data residency is required
- HIPAA eligibility is required
- You need image input / vision
- General knowledge is central to your workload
- Long-context retrieval is central to your workload
Choose GLM-5.1 if…
- Cost is a priority ($1 / $3.2 per 1M vs $2 / $12 per 1M)
- You need open weights for self-hosting or fine-tuning
- You want a free tier for prototyping
Benchmark delta
Gemini 3.1 Pro leads on
- General knowledge
- Long-context retrieval
- Instruction following
- Tool use
GLM-5.1 leads on
GLM-5.1 has no meaningful benchmark lead in this pair.
FAQ — Gemini 3.1 Pro vs GLM-5.1
Gemini 3.1 Pro vs GLM-5.1 — which is better?
Gemini 3.1 Pro and GLM-5.1 are both current production-tier models. GLM-5.1 is meaningfully cheaper at $1 / $3.2 per 1M. Gemini 3.1 Pro has a 2M context window — about 10× the 200k of GLM-5.1. Gemini 3.1 Pro leads on general knowledge, long-context retrieval, instruction following. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does Gemini 3.1 Pro pricing compare to GLM-5.1?
Gemini 3.1 Pro costs $2 / $12 per 1M vs GLM-5.1 at $1 / $3.2 per 1M. GLM-5.1 is cheaper on output tokens by roughly 275%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does Gemini 3.1 Pro or GLM-5.1 have the bigger context window?
Gemini 3.1 Pro has a 2M-token context window — 10× the 200k context of GLM-5.1. Enough for entire codebases, books, or multi-document RAG.
Is there a free tier for Gemini 3.1 Pro or GLM-5.1?
Gemini 3.1 Pro: no — Paid-only since 2026-04-01 (previously had free tier via AI Studio). GLM-5.1: yes — Free tier with monthly token allowance.
Which is better for coding — Gemini 3.1 Pro or GLM-5.1?
Gemini 3.1 Pro leads on coding benchmarks (Gemini 3.1 Pro: 94/100, GLM-5.1: 93/100). For production coding agents also weigh tool-use performance — Gemini 3.1 Pro scores 91, GLM-5.1 scores 86.