Customer churn calculator: what share of your paying accounts did you lose?

Version 1.0.0

Customer churn tells you what share of the paying accounts you had at the start of a period were no longer paying at the end. The basic formula is lost opening accounts ÷ opening paying accounts × 100. You can use it for a completed month, quarter, or another reporting period.

Enter those two counts below to see the rate and how many opening accounts were still paying at the end.

Count active, paying accounts at the start of one reporting period.
Of those opening accounts, count those still not paying at the end. Exclude accounts that joined later.

How to use this calculator

  1. Choose one completed period in your billing report. Count the accounts with an active, billable subscription at the start. Count each account once, even if it has several subscriptions.
  2. Check how many of those same accounts had no active, billable subscription at the end. Leave out accounts that first joined during the period.
  3. Enter both counts as whole numbers. Read the churn percentage alongside the opening, lost, and still-paying account counts.

If your report lists cancellations, check which opening accounts were still lost at the end. Some may have returned to paying status. The calculator asks you to correct a blank or fractional count, or a lost count greater than the opening count.

Which accounts count as lost?

A paying account has at least one active, billable subscription. Leave free trials and free plans out of the opening count, as ChartMogul advises for customer churn.

  • An account paying at the start counts as lost once if none of its subscriptions is active and billable at the end, even if it canceled more than once.
  • An opening account that canceled but returned to paying status by the end is still in the opening group, but is not lost.
  • An account that first joined after the start stays out of both counts, even if it also left before the end.

ChartMogul's churn report also distinguishes customers still canceled at the end from cancellation events during the period. Your billing report may use a different rule, so check its account history before entering a lost count. The calculator cannot do that from two totals.

Calculate and read the rate

Five lost accounts

Say you had 100 paying accounts at the start of a quarter. At the end, five of those accounts are no longer paying. Customer churn for the quarter is 5 ÷ 100 × 100 = 5%, and 95 opening accounts are still paying. Those 95 are not your total customer count at the end if new accounts joined during the quarter.

The still-paying count is the opening count minus the lost count. When comparing churn across periods, use periods of the same length and the same rules for which accounts count.

When the rate is unavailable or very small

If you had no paying accounts at the start, there is no opening count to divide by. With zero opening accounts, the lost count must also be zero, and the calculator shows Unavailable. If you started with paying accounts and lost none, the rate is 0.00%.

A positive rate below 0.01% displays as <0.01% so it cannot be mistaken for zero. For example, one lost account out of 1,000,000 opening accounts is 0.0001%. Check the exact counts in the result when the rate is very small.

Customer churn and revenue churn

Customer churn gives every account the same weight. Losing one large account has the same effect on this rate as losing one small account, even though the revenue lost may differ. ChartMogul explains this difference between customer and revenue churn.

To see how much recurring revenue the customers you started a month with retained, use the net revenue retention calculator. It includes changes from existing customers spending more or less, leaving, or returning. There is no universal target for customer churn because rates vary by product, price point, and company stage.