Churn Rate & Retention Calculator
Calculate customer churn rate and retention rate from customers at the start of a period and customers lost — with an optional annualized rate projection and net-new customer tracking.
Input
How long the period below represents. Annualized rates are derived from this.
Active paying customers at the start of the period.
Customers who churned (cancelled or downgraded to 0) during the period.
New customers acquired during the period. Used for net growth, not for churn rate.
Output
| Metric | Value |
|---|---|
| No data yet | |
Guides
What is customer churn rate?
Churn rate is the percentage of customers you lose during a period, relative to how many you started with:
Churn Rate % = (Customers Lost ÷ Customers at Start) × 100
Retention rate is simply the flip side — the percentage of customers you kept:
Retention Rate % = 100% − Churn Rate %
If you started the month with 1,000 customers and lost 50, your churn rate is 5% and your retention rate is 95%.
Why churn and retention matter
For subscription and SaaS businesses, churn is one of the most important health metrics there is. A small monthly churn rate compounds over a year: even a "modest" 5% monthly churn means you're losing roughly 46% of your customer base annually if nothing offsets it, because churn compounds period over period rather than adding up linearly. This calculator projects that annualized figure automatically whenever you pick a monthly or quarterly period, using the standard compounding formula 1 − (1 − periodChurn)^periodsPerYear.
Retention, meanwhile, drives long-term revenue and growth efficiency — it's usually far cheaper to keep an existing customer than to acquire a new one, so a few points of retention can be worth more than an equivalent bump in new signups.
How to use this calculator
- Choose your period length — monthly, quarterly, or annual. This determines whether an annualized projection is shown.
- Enter customers at the start of the period — your active, paying customer count on day one of the period.
- Enter customers lost — how many of those customers cancelled or churned out during the period.
- Optionally enter new customers acquired — this doesn't change your churn rate (churn is only about the customers you started with), but it lets the calculator also show your net new customer count and ending customer total.
Results update instantly as you type — no need to click a button.
Frequently asked questions
Does churn rate include new customers? No. Churn rate is calculated only from the customers you had at the start of the period, so new signups can't dilute or hide churn. This is standard practice — mixing in new customers would understate how much of your existing base is leaving.
What if I enter more customers lost than I started with? The calculator will still compute the result, which produces a churn rate above 100%. That normally signals a data entry error — double-check your start-of-period count.
Why does the annualized rate look so much higher than my monthly rate?
Churn compounds. Losing 5% of your customers every month for 12 months in a row doesn't add up to 60% — it works out to roughly 46%, because each month's churn is applied to a shrinking base and the compounding math (1 − (1 − r)^n) reflects that. Annual-period inputs skip this projection since there's nothing to annualize.
Is this the same as revenue churn or MRR churn? No — this tool measures customer count churn and retention. Revenue-based churn (Net/Gross Revenue Retention) tracks dollars lost or kept instead of headcount, and can move independently of customer churn (for example, if the customers who leave are disproportionately small accounts).
Privacy
All calculations run entirely in your browser. Your customer counts are never uploaded or stored anywhere.