Customer Retention Rate Calculator
Retention is what churn leaves behind. Lose 42 of 1,200 and churn is 3.5%, retention 96.5%. The catch is that the 96.5% multiplies every month — 0.965 to the twelfth power is 65.2%, so only 783 of the 1,200 are still there. The impression 96.5% gives and the share actually left after a year are that far apart.
Your numbers
Monthly retention
96.5%
Retention after the period
65.2%
Customers after the period
783
Monthly churn
3.5%
Formula
Monthly retention = 100 − Monthly churn, Retention after the period = (Monthly retention ÷ 100) ^ Months × 100
You cannot turn monthly retention into yearly retention by subtracting or multiplying by twelve — it has to be a power. Lifting 96.5% to 99% turns 65.2% after twelve months into 88.6%, and those 2.5 points move lifetime value by close to 40%. Customers who leave and come back are not in this arithmetic, so where reactivation is common the real remaining share is higher.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Customers at startCustomers you had at the start of the month; this month's signups are out. | 1,200 | 0 and up |
| Customers lostCustomers who left during the month; a headcount, not a revenue figure. | 42 | 0 and up |
| Months (mo)The period counted in months; a yearly rate gets divided by twelve. | 12 | 0 ~ 120 |
Step by step
Quick reference table
Results when only Customers at start changes and everything else stays put.
| Customers at start | Monthly retention (%) | Retention after the period (%) | Customers after the period |
|---|---|---|---|
| 600 | 93 | 41.9 | 251 |
| 900 | 95.33 | 56.4 | 507 |
| 1,200 | 96.5 | 65.2 | 783 |
| 1,800 | 97.67 | 75.3 | 1,356 |
| 2,400 | 98.25 | 80.9 | 1,942 |
What each result means
| Result | At default values |
|---|---|
| Monthly retention (%)The share still there a month later — what churn leaves behind. | 96.5 |
| Retention after the period (%)What monthly retention compounds to over the period — a power, not a subtraction. | 65.2 |
| Customers after the periodCustomers left after that period; reactivations are not counted. | 783 |
| Monthly churn (%)The share of starting customers who left; inverted, it gives the average lifetime. | 3.5 |
Common mistakes
You cannot turn monthly retention into yearly retention by subtracting or multiplying by twelve — it has to be a power. Lifting 96.5% to 99% turns 65.2% after twelve months into 88.6%, and those 2.5 points move lifetime value by close to 40%. Customers who leave and come back are not in this arithmetic, so where reactivation is common the real remaining share is higher.
Glossary
- Customers at start
- Customers you had at the start of the month; this month's signups are out.
- Customers lost
- Customers who left during the month; a headcount, not a revenue figure.
- Months
- The period counted in months; a yearly rate gets divided by twelve.
- Monthly retention
- The share still there a month later — what churn leaves behind.
- Retention after the period
- What monthly retention compounds to over the period — a power, not a subtraction.
- Customers after the period
- Customers left after that period; reactivations are not counted.
- Monthly churn
- The share of starting customers who left; inverted, it gives the average lifetime.
Frequently asked questions
Q. How is Customer Retention Rate Calculator calculated?
Monthly retention = 100 − Monthly churn, Retention after the period = (Monthly retention ÷ 100) ^ Months × 100 — Retention is what churn leaves behind. Lose 42 of 1,200 and churn is 3.5%, retention 96.5%. The catch is that the 96.5% multiplies every month — 0.965 to the twelfth power is 65.2%, so only 783 of the 1,200 are still there. The impression 96.5% gives and the share actually left after a year are that far apart.
Q. Can you walk through an example?
With Customers at start 1,200, Customers lost 42, Months 12mo, the answer is Monthly retention 96.5%.
Q. What do I need to enter?
Enter Customers at start, Customers lost, Months. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Customers at start moves the answer to Customers at start 600 → Monthly retention (%) 93 and Customers at start 2,400 → Monthly retention (%) 98.25. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
You cannot turn monthly retention into yearly retention by subtracting or multiplying by twelve — it has to be a power. Lifting 96.5% to 99% turns 65.2% after twelve months into 88.6%, and those 2.5 points move lifetime value by close to 40%. Customers who leave and come back are not in this arithmetic, so where reactivation is common the real remaining share is higher.
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