Free Tool
SaaS Churn Calculator
Churn is two numbers, not one: the customers who left, and the revenue that left with them. This calculator shows both — and the average lifetime the churn rate implies.
Planning estimate, not financial advice. All figures on this page are estimates or scenarios for planning purposes only, built from the numbers you enter. They are not financial, tax or legal advice, and no earnings are promised. Read the full financial disclaimer.
What this tool does
Enter the customers at the start of the month, how many left, the MRR at the start, how much MRR was lost to cancellations and downgrades, and how much came back through expansion. The calculator returns the customer churn rate, the gross and net revenue churn rates, and the average customer lifetime implied by the churn rate.
Gross and net revenue churn are different stories. Gross churn counts only what was lost; net churn subtracts the expansion from existing customers, and can go negative — which means the remaining customers are now paying more than the ones who left. A business with 5% gross churn and negative net churn is growing from its existing base, not shrinking.
Try it
Waiting. Enter the customers and MRR at the start, and what was lost and gained, then press Calculate.
How it works
Customer churn is customers lost divided by customers at the start, times one hundred. Gross revenue churn is MRR lost divided by MRR at the start, times one hundred. Net revenue churn is MRR lost minus expansion MRR, divided by MRR at the start, times one hundred. Average lifetime is one hundred divided by the customer churn percentage — the months a customer stays, on average, at a steady churn rate.
Lifetime is an average, not a promise about any one customer. At 5% monthly churn the average customer stays 20 months; half stay less than that, and a few stay far longer.
Assumptions and limitations
Churn is a monthly rate from your own billing records — not a benchmark.
- All figures are monthly, from your own billing records. Annual churn and monthly churn are different numbers and must not be mixed.
- Customer churn and revenue churn differ when big customers leave. Losing six small customers and losing one large one are different events — the revenue figure shows which one happened.
- Lifetime assumes the churn rate stays steady. It moves as the rate moves, and early months with few customers make it jump around.
- Expansion counts upgrades from customers who stayed. New customers are not expansion — they belong in the MRR calculator, not in the churn rate.
Worked example
Example (illustrative inputs, not a real product). 120 customers, 6 lost, 3,480 MRR at start, 200 MRR lost, 300 expansion:
| Item | Figure |
|---|---|
| Customer churn (6 ÷ 120) | 5.00% a month |
| Gross revenue churn (200 ÷ 3,480) | 5.75% a month |
| Net revenue churn ((200 − 300) ÷ 3,480) | −2.87% a month |
| Average customer lifetime (100 ÷ 5) | 20.0 months |
Frequently asked questions
What is the difference between gross and net revenue churn?
Gross churn counts only what was lost to cancellations and downgrades. Net churn subtracts the expansion revenue from customers who stayed — upgrades and extra seats. Net churn can go negative, which means the remaining base now pays more than before.
Why can net churn be negative?
Because expansion outgrew the loss. If 200 of MRR churned but 300 came back as upgrades from existing customers, the base is 100 ahead despite the cancellations. Negative net churn is the sign of a product that grows inside its own customers.
How is lifetime worked out from churn?
One hundred divided by the monthly churn percentage. At 5% monthly churn the average customer stays 20 months. It is an average at a steady rate — not a promise about any single customer.
Should I use monthly or annual churn?
Monthly, for a subscription business — it is the rate the business is actually managed on. Annual churn hides the months that went wrong. Be consistent: monthly inputs, monthly rate, monthly lifetime.