DeepSeek V4 Flash vs GLM-5.1
DeepSeek V4 Flash and GLM-5.1 are both current production-tier models. DeepSeek V4 Flash is meaningfully cheaper at $0.14 / $0.28 per 1M. DeepSeek V4 Flash has a 1M context window — about 5× the 200k of GLM-5.1. DeepSeek V4 Flash leads on long-context retrieval. GLM-5.1 leads on coding, multilingual.
Specs side by side
| Metric | DeepSeek DeepSeek V4 Flash | Z.ai GLM-5.1 |
|---|---|---|
| Input price (per 1M) | $0.14 | $1.4 |
| Output price (per 1M) | $0.28 | $4.4 |
| Context window | 1M tokens | 200k tokens |
| Speed tier | balanced | balanced |
| Open weights | Yes | Yes |
| EU region | No | No |
| Free tier | OpenRouter | bigmodel.cn |
| Prompt caching | Yes | No |
| Vision input | No | No |
| Extended thinking | Yes | Yes |
When to choose each
Choose DeepSeek V4 Flash if…
- Cost is a priority ($0.14 / $0.28 per 1M vs $1.4 / $4.4 per 1M)
- You need 1M context (5× more than GLM-5.1)
- Long-context retrieval is central to your workload
Choose GLM-5.1 if…
- Coding is central to your workload
- Multilingual is central to your workload
Benchmark delta
DeepSeek V4 Flash leads on
- Long-context retrieval
GLM-5.1 leads on
- Coding
- Multilingual
FAQ — DeepSeek V4 Flash vs GLM-5.1
DeepSeek V4 Flash vs GLM-5.1 — which is better?
DeepSeek V4 Flash and GLM-5.1 are both current production-tier models. DeepSeek V4 Flash is meaningfully cheaper at $0.14 / $0.28 per 1M. DeepSeek V4 Flash has a 1M context window — about 5× the 200k of GLM-5.1. DeepSeek V4 Flash leads on long-context retrieval. GLM-5.1 leads on coding, multilingual. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does DeepSeek V4 Flash pricing compare to GLM-5.1?
DeepSeek V4 Flash costs $0.14 / $0.28 per 1M vs GLM-5.1 at $1.4 / $4.4 per 1M. DeepSeek V4 Flash is cheaper on output tokens by roughly 1471%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does DeepSeek V4 Flash or GLM-5.1 have the bigger context window?
DeepSeek V4 Flash has a 1M-token context window — 5× the 200k context of GLM-5.1. Enough for entire codebases, books, or multi-document RAG.
Is there a free tier for DeepSeek V4 Flash or GLM-5.1?
DeepSeek V4 Flash: yes — Often available free via OpenRouter; official API is extremely cheap ($0.14 cache miss, $0.0028 cached input). GLM-5.1: yes — Free tier with monthly token allowance.
Which is better for coding — DeepSeek V4 Flash or GLM-5.1?
GLM-5.1 leads on coding benchmarks (DeepSeek V4 Flash: 89/100, GLM-5.1: 93/100). For production coding agents also weigh tool-use performance — DeepSeek V4 Flash scores 84, GLM-5.1 scores 86.