Monthly churn and annual churn measure the same loss across different windows, and converting between them requires compounding rather than multiplication. Annual churn equals 1 minus (1 minus monthly churn) raised to the twelfth power. A monthly rate multiplied by 12 always overstates the annual figure, because each month can only lose customers who survived the months before it.
The conversion formula
Annual churn = 1 - (1 - monthly churn)^12
At 2% monthly churn, monthly survival is 0.98. Compounded over twelve months, survival lands at 0.785, so annual churn is 21.5%. The multiplication shortcut returns 24%. The gap widens fast as the rate climbs. At 5% monthly churn, compounding gives 46.0% annual churn while multiplication gives 60%, a 14-point error large enough to reshape any plan built on it.
The conversion runs in reverse with a twelfth root. Monthly churn = 1 - (1 - annual churn)^(1/12). A 15% annual churn assumption handed down from finance translates to 1.35% monthly, not the 1.25% that dividing by 12 produces.
Which window belongs in which report
Contract length decides the reporting window. A self-serve product billed monthly gives every customer twelve chances to cancel, so monthly churn is the operating metric and the compounded figure is the planning metric. Annual contracts give a customer one cancellation decision per year, which turns monthly churn into a byproduct of renewal timing. A business on annual contracts can post 0% churn in March and 8% in April with nothing changing in the underlying base.
Mixed books need the calculation run per segment. Net revenue retention reported at the company level buries the difference, because a monthly self-serve base and an annual enterprise base do not behave alike and should never be averaged into one rate.
Where the compounding assumption breaks
The formula assumes a constant hazard rate, meaning every month carries the same probability of loss. Real cohorts violate that. Cancellations concentrate in the first months after purchase and thin out as tenure builds, so a single blended monthly rate applied across twelve months understates early loss and overstates late loss. Cohort curves fix it. Measure churn by month of tenure, then apply the curve to each cohort rather than one rate to everyone.
Revenue churn adds a second wrinkle. Downgrades cut revenue without removing a customer, and expansion offsets losses the churn number never sees. Run the compounding math on logo churn and gross revenue churn separately, then read expansion on its own line when you build the revenue forecast.
Frequently Asked Questions
How do you convert monthly churn to annual churn?
Compound the survival rate. Annual churn = 1 - (1 - monthly churn) raised to the twelfth power. At 2% monthly churn, survival is 0.98 per month, which compounds to 0.785 over twelve months, so annual churn is 21.5%.
Why can you not multiply monthly churn by 12?
Because each month can only lose customers who survived the previous months. Multiplying applies the rate to the full starting base twelve times over, which double-counts accounts that already left. At 5% monthly churn the shortcut returns 60% annual churn when the correct answer is 46.0%.
How do you go from annual churn back to a monthly rate?
Take the twelfth root of survival. Monthly churn = 1 - (1 - annual churn) raised to the power of one twelfth. A 15% annual churn assumption becomes 1.35% monthly, not the 1.25% that dividing by 12 produces.
Should a SaaS company report monthly or annual churn?
Contract length decides. Monthly billing gives a customer twelve cancellation decisions a year, so monthly churn is the operating number. Annual contracts give one decision a year, which makes monthly churn an artifact of when renewal dates fall rather than a measure of customer behavior.
Put these metrics to work
ORM builds custom revenue forecast models that turn concepts like monthly churn to annual churn into prescriptive action for your team.
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