Claude Fable 5 vs GLM-5.1
Claude Fable 5 and GLM-5.1 are both current production-tier models. GLM-5.1 is meaningfully cheaper at $1.4 / $4.4 per 1M. Claude Fable 5 has a 1M context window — about 5× the 200k of GLM-5.1. Claude Fable 5 leads on coding, reasoning, general knowledge.
Specs side by side
| Metric | Anthropic Claude Fable 5 | Z.ai GLM-5.1 |
|---|---|---|
| Input price (per 1M) | $10 | $1.4 |
| Output price (per 1M) | $50 | $4.4 |
| Context window | 1M tokens | 200k tokens |
| Speed tier | slow | balanced |
| Open weights | No | Yes |
| EU region | Yes | No |
| Free tier | No | bigmodel.cn |
| Prompt caching | Yes | Yes |
| Vision input | Yes | No |
| Extended thinking | Yes | Yes |
When to choose each
Choose Claude Fable 5 if…
- You need 1M context (5× more than GLM-5.1)
- EU data residency is required
- HIPAA eligibility is required
- You need image input / vision
- Coding is central to your workload
- Reasoning is central to your workload
Choose GLM-5.1 if…
- Cost is a priority ($1.4 / $4.4 per 1M vs $10 / $50 per 1M)
- You need open weights for self-hosting or fine-tuning
- You want a free tier for prototyping
Benchmark delta
Claude Fable 5 leads on
- Coding
- Reasoning
- 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 — Claude Fable 5 vs GLM-5.1
Claude Fable 5 vs GLM-5.1 — which is better?
Claude Fable 5 and GLM-5.1 are both current production-tier models. GLM-5.1 is meaningfully cheaper at $1.4 / $4.4 per 1M. Claude Fable 5 has a 1M context window — about 5× the 200k of GLM-5.1. Claude Fable 5 leads on coding, reasoning, general knowledge. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does Claude Fable 5 pricing compare to GLM-5.1?
Claude Fable 5 costs $10 / $50 per 1M vs GLM-5.1 at $1.4 / $4.4 per 1M. GLM-5.1 is cheaper on output tokens by roughly 1036%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does Claude Fable 5 or GLM-5.1 have the bigger context window?
Claude Fable 5 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 Claude Fable 5 or GLM-5.1?
Claude Fable 5: no — No free API tier; available via Claude.ai paid plans. GLM-5.1: yes — Free tier with monthly token allowance.
Which is better for coding — Claude Fable 5 or GLM-5.1?
Claude Fable 5 leads on coding benchmarks (Claude Fable 5: 98/100, GLM-5.1: 93/100). For production coding agents also weigh tool-use performance — Claude Fable 5 scores 97, GLM-5.1 scores 86.