The two words get used interchangeably, and in most rooms that is fine. But if you are reading a finance report or a SaaS benchmarking study, the distinction does matter. Attrition tends to mean the cumulative customer loss across a defined population. Churn tends to mean the rolling rate at which that loss happens.
The practical difference
- Attrition is often expressed as an annual figure and includes all reasons for departure — cancellation, non-renewal, account closure, death of a contract. HR and finance teams use it the same way they talk about employee attrition.
- Churn is the subscription-native term. It is usually monthly, sometimes quarterly, and almost always split into voluntary and involuntary categories so you can fix the right problem.
If a board deck says "annual attrition was 22%," that is a backward-looking statement about the year. If an ops dashboard says "monthly churn is 4%," that is a live operating metric you can act on this week.
Which one should subscription merchants track?
Both, but for different audiences. For day-to-day operations, track monthly customer churn and monthly MRR churn — these tell you whether your fixes are working. For investor updates and annual planning, attrition (or 12-month retention) gives the trend the leadership team needs to see.
A common mistake
People translate "5% monthly churn" into "60% annual attrition" with simple multiplication. That overstates the loss because the base shrinks each month. Actual annual attrition from 5% monthly churn is closer to 46% — still painful, but the math is compounding decay, not linear addition. Use the formula 1 − (1 − monthly_churn)^12 to convert correctly.