Customer Churn Calculator

Enter your customers at the start of a period and how many you lost. Instantly see your churn rate, retention rate, optional MRR revenue churn, and where your customer count lands in 12 months if nothing changes. Everything runs privately in your browser.

📖 How it works & FAQ

Customers at start of period

Customers lost during period

Period length

MRR at start ($, optional)

MRR lost to churn ($, optional)

What customer churn actually tells you

Churn rate is the percentage of customers who cancel or stop paying during a period. The formula is simple: customers lost divided by customers at the start of the period, times 100. Retention rate is the mirror image — 100 minus churn. A SaaS business losing 25 of 500 customers in a month has 5% monthly churn and 95% retention. That sounds small until you compound it: at 5% monthly churn, roughly 46% of your customer base disappears within a year. This calculator does that compounding for you, projecting your customer count 12 months out at your current rate.

If you enter your MRR figures, it also computes revenue churn — the share of monthly recurring revenue lost to cancellations. Revenue churn often differs from customer churn because bigger accounts churn at different rates than small ones. Figures here are estimates only, not professional or financial advice; every business defines and measures churn a little differently.

How to use it

Enter the number of customers you had at the start of the period.
Enter how many of those customers you lost during the period (cancellations, non-renewals).
Pick the period length — monthly, quarterly, or annual — so the 12-month projection compounds correctly.
Optionally add MRR at the start and MRR lost to churn to see revenue churn. Results update live as you type.

FAQ

Do new customers count in the churn rate?: No. The standard formula only compares customers lost against customers at the start of the period. New signups affect growth, not churn. Only count losses from the starting cohort.
What is a good churn rate for SaaS?: Rules of thumb: 3–7% monthly is common for early-stage SMB SaaS, while mature companies target under 1% monthly. Enterprise products usually track annual churn of 5–10% instead.
Why is my revenue churn different from customer churn?: Because customers pay different amounts. Losing a few large accounts can push revenue churn well above customer churn — and expansion revenue from upgrades can even make net revenue churn negative.
How is the 12-month projection calculated?: It compounds your retention rate: starting customers × (1 − churn rate) raised to the number of periods in 12 months. It assumes the rate stays constant and ignores new customer acquisition.