Retention and attrition describe the same reality from opposite sides. A 92% monthly retention rate and an 8% monthly attrition rate are the same fact stated two ways. Which word a team prefers tends to reveal its culture — finance and HR lean toward attrition (loss framing), product and customer success lean toward retention (success framing).
How they relate mathematically
For any period: retention + attrition = 100%. That holds for customer count and for revenue. So:
- If 950 of 1,000 starting customers remain at month-end, monthly retention is 95% and monthly attrition is 5%.
- If $19,000 of $20,000 starting MRR remains, revenue retention is 95% and revenue attrition is 5%.
One caveat: net revenue retention can exceed 100% because expansion revenue from existing customers offsets losses. In that case, revenue attrition stays positive (you still lose some revenue) while net retention shows the offsetting growth.
When the words diverge
In practice, the two terms get used for slightly different time horizons:
- Retention is usually measured monthly or by cohort vintage. Subscription operators say "3-month retention," "6-month retention," etc.
- Attrition is more often an annual figure, especially in HR and finance reports. "Annual attrition of 22%" reads like a yearly verdict.
- Churn is the subscription-native cousin of attrition, almost always reported monthly, almost always split by voluntary / involuntary cause.
Which word should subscription merchants use?
Retention. Two reasons. First, it focuses internal attention on the customers you have rather than the ones you lost — which leads to better operational decisions. Second, the customer-facing language reads better: "our 90-day retention is 88%" tells a positive story; "our 90-day attrition is 12%" tells the same story negatively. The math is identical, but the framing influences how teams act on it.
For the operating metric details, see customer retention rate and churn; for the long-form comparison, see attrition vs. churn.