# Subscription Churn Impact Calculator

> Churn calculator: measure how subscription churn cuts monthly recurring revenue and lifetime value, and what retention gains are worth. Free, no signup.

- **Canonical URL:** https://boringtoolskit.com/subscription-churn-impact-calculator/
- **Category:** Seller & Business
- **Evidence level:** authored-methodology
- **Reviewed:** July 2026
- **Last verified:** 2026-09-20
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

Each month, churned customers = opening customers × monthly churn; ending customers = opening customers − churned customers + new customers. Monthly revenue = ending customers × ARPU.

## Worked example

1,000 customers, 5% monthly churn, no acquisition, and $20 ARPU leave about 540 customers and $10,807 monthly revenue after 12 modeled months.

## Assumptions

- Churn, acquisition, and ARPU remain constant throughout the horizon.
- Churn is applied before new customers are added each month.
- Cohorts, expansion revenue, reactivation, seasonality, failed payments, and acquisition lag are excluded.

## Common questions

### When is churn applied?

To opening customers before the entered new customers are added.

### What is replacement need?

Month-one customers expected to churn at the entered rate; rounding up gives a whole-customer planning target.

### Is this a retention forecast?

No. It is a bounded constant-rate scenario without cohort behavior.

## Related tools

- /customer-lifetime-value-calculator/
- /cash-flow-runway-calculator/
- /price-increase-impact-calculator/

## Sources

- [Marketing and sales](https://www.sba.gov/business-guide/manage-your-business/marketing-sales)

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