Z.ai: GLM 5.1 API Pricing
Z.ai: GLM 5.1 costs $1.40 per 1M input tokens and $4.40 per 1M output tokens (cache reads: $0.260). Context window: 205K. Prices verified 2026-10-21 · source
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Token economics
| Token type | Price | vs base input |
|---|---|---|
| Standard input | $1.40 | — |
| Cache read | $0.260 | −81% |
| Output | $4.40 | — |
Prompt caching stores repeated context server-side: reads cost far less, but writes carry a one-time premium.
Higher effort = deeper thinking = more reasoning tokens billed as output.
What would Z.ai: GLM 5.1 cost you per month?
| Workload | Requests/mo | Avg tokens (in/out) | Est. monthly cost |
|---|---|---|---|
| Light chatbot | 10,000 | 800 / 400 | $28.80 |
| Coding agent | 5,000 | 8,000 / 2,000 | $100.00 |
| RAG pipeline | 30,000 | 4,000 / 500 | $234.00 |
| Doc summarizer | 2,000 | 20,000 / 1,000 | $64.80 |
Estimates use list prices without prompt caching. Caching can cut input cost by up to 90% on repeated context.
About Z.ai: GLM 5.1
GLM-5.1 delivers a major leap in coding capability, with particularly significant gains in handling long-horizon tasks. Unlike previous models built around minute-level interactions, GLM-5.1 can work independently and continuously on...
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Frequently asked questions
How much does Z.ai: GLM 5.1 cost?
Z.ai: GLM 5.1 costs $1.40 per 1M input tokens and $4.40 per 1M output tokens; cached input tokens cost $0.260 per 1M. Verified 2026-10-21 — provider source.
What is the context window?
205K tokens, with up to 131K output tokens per response. That's roughly 256 pages of text in a single request.
Does it support prompt caching?
Yes — cached input is $0.260/1M, about 81% cheaper than standard input. Agents and RAG workloads with repeated context benefit most.
What's a cheaper alternative?
ScaleDown: Summarize saves about 99% on a typical workload with comparable quality.
Official resources
- Z.ai: GLM 5.1 on OpenRouter — live endpoint, pricing source of record.
- Artificial Analysis leaderboard → — independent intelligence and performance rankings.
- Shred your current bill — paste a CSV and see if switching saves money.