How churn rate is measured
Customer churn rate answers a deceptively simple question: of the customers you had at the start of a period, what fraction had left by the end? You take the number of customers lost, divide it by the number you began with, and express the result as a percentage. Retention is just the other side of the same coin — a 5% churn rate means 95% of customers stayed. The figure looks straightforward, but its meaning hinges entirely on the period you pick and the denominator you count, which is where most of the confusion creeps in.
The churn formula
Churn rate = customers lost ÷ customers at start × 100%
Retention rate = 100% − churn rate
where customers lost counts those who left during the period and customers at start is the base you measure against. If you begin a month with 500 customers and lose 25, churn is 5% and retention is 95%.
Worked example
Take a subscription business that starts the month with 1,000 customers and sees 50 of them cancel before the month ends:
| Step | Amount |
|---|---|
| Customers at start of the month | 1,000 |
| − Customers lost during the monthcancellations counted over the period | 50 |
| Retention rate950 of 1,000 customers stayed — 100% minus churn | 95.00% |
| = Monthly churn rateleft to compound for a year, this rate keeps only 54.0% of the starting customer base | 5.00% |
Computed with this calculator's default settings — open the tool above and you'll see the same numbers, then swap in your own customer counts.
Why churn compounds and why it sets the ceiling on value
The danger of churn is that it compounds. A 5% monthly churn rate sounds modest, but each month it takes a slice of the customers who survived the previous month. Over a year you retain 0.95 raised to the twelfth power, which is about 54% — meaning you lose roughly 46% of your customers in twelve months. Monthly and annual churn are therefore not interchangeable, and reading one as if it were the other is one of the easiest ways to badly misjudge a business.
Churn also acts as the hard ceiling on customer lifetime value. The average customer lifespan is simply 1 divided by the churn rate, so a 5% monthly churn implies an average life of about 20 months. Lifetime value follows directly: LTV equals the gross margin per period divided by churn. Because churn sits in the denominator, halving it roughly doubles both expected lifespan and lifetime value. That leverage is why retention work often pays off more than chasing new customers. You can explore both sides with ourretention rate calculatorandLTV calculator.
Pitfalls and the flavours of churn
- Customer churn versus revenue churn. Customer churn counts heads, treating every account as equal. Revenue churn counts dollars, weighting each customer by what they pay. If the accounts that leave are small, customer churn can look alarming while revenue churn stays mild — and the reverse is just as possible.
- Gross versus net churn. Gross churn measures only the revenue or customers lost. Net churn subtracts the expansion you gain from existing customers upgrading, and it can even turn negative when upgrades outweigh losses. Both are honest measures, but they answer different questions, so be explicit about which one you are quoting.
- The period and the denominator. Monthly and annual churn are not the same number, and they do not convert by simple multiplication. Equally, the customer count you divide by — start of period, average over the period, or end of period — changes the result. Pick one definition and apply it consistently.
Frequently asked questions
What is churn rate?
Churn rate is the percentage of customers you lose over a given period. You measure it by comparing how many customers leave during the period to how many you had at the start. It is the mirror image of retention: if 5% of your customers churn, 95% are retained. Because it captures the rate at which a business leaks customers, churn is one of the most important health metrics for any subscription or recurring-revenue company.
How do you calculate churn rate?
Divide the number of customers lost during the period by the number of customers you had at the start of that period, then multiply by 100 to express it as a percent. For example, if you began the month with 500 customers and 25 of them cancelled, your monthly churn rate is 25 divided by 500, or 5%. The retention rate for the same period is simply 100% minus the churn rate, so 95% in this case.
What is a good churn rate?
It depends heavily on the type of business and the length of the period, so there is no single benchmark. As a rough guide, many healthy subscription businesses aim for monthly customer churn in the low single digits, often around 1% to 2%, while annual churn in the range of 5% to 10% is common for sticky products. Consumer apps usually churn faster than enterprise software. The most useful comparison is against your own past performance and the lifetime value the churn rate implies, not against a generic target.
How does monthly churn compound annually?
Monthly churn compounds because each month you lose a slice of the customers who remained after the previous month, not of your original base. A 5% monthly churn rate does not add up to 60% over twelve months. Instead you retain 95% each month, so after a year you keep 0.95 raised to the twelfth power, which is about 54%. That means you lose roughly 46% of your customers over the year. This compounding is why even small monthly churn numbers translate into large annual losses.
What is the difference between customer churn and revenue churn?
Customer churn counts how many customers you lose, treating every customer as equal. Revenue churn measures how many dollars of recurring revenue you lose, which weights each customer by what they pay. The two can diverge sharply: if the customers who leave are mostly small accounts, your customer churn can look high while your revenue churn stays low, and vice versa. Revenue churn also has gross and net versions, where net churn subtracts expansion revenue from existing customers and can even turn negative when upgrades outweigh losses.
Disclaimer: This calculator is foreducation and illustration only. Churn rate depends on how you define the period and the customer base, and a single percentage cannot capture every nuance of a business. The figures it produces are not forecasts or valuations of any specific company. Nothing here is investment, tax, or business advice.