# What is Churn Rate? Definition & Technical Mechanics

> **Source:** [SPIDITS AI Startup & Venture Intelligence Glossary](https://spidits.com/startup-glossary)  
> **Category:** Metrics  
> **Canonical Citation:** [https://spidits.com/startup-glossary/churn-rate](https://spidits.com/startup-glossary/churn-rate)

## Definition
Churn Rate is the percentage of customers or subscription revenue that a startup loses over a specified period.

## Architectural Mechanics & Deep Dive
Churn Rate is the percentage of customers or subscription revenue that a startup loses over a specified period. High churn rates are dangerous as they make growth expensive by constantly depleting the customer base.

## Industry Applications & Real-World Use Cases
Customer retention and satisfaction metrics

## Frequently Asked Questions

### How is churn rate calculated?
Customers lost during period divided by starting customers in that period.

### Why is a high churn rate dangerous?
It makes growth expensive; if you lose customers as fast as you acquire them, you are spending money on a leaky bucket.

## Related Terminology
- [nrr](https://spidits.com/startup-glossary/nrr)
- [ltv](https://spidits.com/startup-glossary/ltv)
- [cac](https://spidits.com/startup-glossary/cac)

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*From the SPIDITS AI Knowledge Base (300+ terms indexed). Explore full technical definitions: [https://spidits.com/startup-glossary](https://spidits.com/startup-glossary)*