Churn Rate Calculator
Created by: Emma Collins
Last updated:
Calculate monthly and annualized customer churn from start, end, and new customer counts, plus retention rate, average customer lifespan, and revenue impact at your ARPU.
Churn Rate Calculator
FinanceCalculate monthly and annualized customer churn rate, retention rate, average customer lifespan, and revenue impact.
Total customer count at the beginning of the period
Total customer count at the end of the period
New customers gained during the same period
Optional — used to estimate revenue impact
What Is a Churn Rate Calculator?
A Churn Rate Calculator measures the percentage of customers a business loses over a given period by comparing customers at the start of the period, new customers acquired during it, and customers remaining at the end.
The core formula — customers lost = start + new − end — correctly isolates attrition from growth, so the result reflects true customer loss even when total customer count is rising due to active acquisition.
Beyond the headline monthly churn percentage, this calculator also projects annualized churn (what 12 consecutive months of the same monthly rate would compound to), customer retention rate, and average customer lifespan — a figure derived directly from churn rate that feeds into customer lifetime value (CLV) calculations.
An optional average revenue per user (ARPU) input converts churn from an abstract percentage into a concrete monthly and annual revenue impact figure.
Churn is one of the single most important health metrics for subscription, membership, and recurring-revenue businesses, since the cost of acquiring a new customer is typically far higher than the cost of retaining an existing one.
Even small differences in monthly churn rate compound dramatically over a year due to the exponential nature of the annualization formula.
How Churn Rate and Related Metrics Are Calculated
Customers lost is calculated as customers at start plus new customers acquired minus customers at end.
Monthly churn rate is customers lost divided by customers at start, expressed as a percentage.
Annualized churn rate compounds the monthly rate across 12 periods using 1 − (1 − monthly churn rate)^12, since simple multiplication by 12 would overstate the true cumulative effect.
Retention rate is simply 100% minus monthly churn rate, and average customer lifespan in months is approximately 100 divided by the monthly churn percentage.
Revenue impact multiplies customers lost by ARPU for a monthly figure, then by 12 for an annualized estimate.
Churn Rate Formulas
Customers lost = customers at start + new customers − customers at end
Monthly churn rate % = (customers lost / customers at start) × 100
Annualized churn rate % = [1 − (1 − monthly churn rate)^12] × 100
Retention rate % = 100% − monthly churn rate %
Average customer lifespan (months) = 100 / monthly churn rate %
Monthly revenue impact = customers lost × ARPU
Example Scenarios
Healthy B2B SaaS Month
Customers at start: 800. New customers: 40. Customers at end: 820. Customers lost: 800 + 40 − 820 = 20. Monthly churn rate: 20 / 800 = 2.5%. Annualized churn: roughly 26%. Average customer lifespan: 100 / 2.5 ≈ 40 months. At an ARPU of $120/month, the monthly revenue impact is $2,400, or about $28,800 annually if the pattern continues — a useful number for prioritizing retention investment against acquisition spend.
Consumer Subscription with Higher Churn
Customers at start: 5,000. New customers: 600. Customers at end: 5,200. Customers lost: 5,000 + 600 − 5,200 = 400. Monthly churn rate: 400 / 5,000 = 8%. Annualized churn: roughly 63% — meaning at this pace, nearly two-thirds of the current customer base would churn out over a year if unaddressed. Average customer lifespan: 100 / 8 = 12.5 months, a clear signal that retention initiatives like onboarding improvements or loyalty programs are likely a higher priority than further acquisition spend.
How People Use This Calculator
- SaaS founders and operators tracking monthly churn as a core health metric for investor updates and board reporting.
- Customer success teams measuring whether retention initiatives like onboarding changes are reducing churn over time.
- Subscription box and membership businesses converting churn percentage into concrete monthly revenue-at-risk figures.
- Finance teams modeling revenue forecasts that account for expected customer attrition alongside new bookings.
- Product teams correlating churn spikes with specific releases, pricing changes, or onboarding flow updates.
- Investors and analysts evaluating subscription business health during due diligence using annualized churn benchmarks.
Tips for Tracking and Reducing Churn
Measure churn consistently on a fixed period — monthly is most common — and track it as a trend line rather than a single snapshot, since one unusually high or low month can be misleading without the surrounding context of several months of data.
Segment churn by customer cohort, plan tier, or acquisition channel whenever possible.
A blended churn rate can mask the fact that one segment (for example, customers acquired through a discount promotion) churns at a much higher rate than your core base, and averaging the two together hides where the real retention problem lives.
Frequently Asked Questions
What is customer churn rate?
Customer churn rate is the percentage of customers who stop doing business with you over a given period, typically a month. It is calculated as customers lost divided by customers at the start of the period, multiplied by 100. Churn is one of the most important health metrics for subscription and membership businesses because even small increases compound into large revenue losses over time.
How do you calculate customers lost when new customers were also acquired?
Customers lost = customers at start + new customers acquired during the period − customers at the end of the period. This formula correctly isolates churn from growth: if you started with 500 customers, added 50 new ones, and ended with 520, you actually lost 30 customers (500 + 50 − 520), even though your total customer count grew. Simply comparing start and end counts would understate churn whenever new acquisition is happening.
What is the difference between monthly and annualized churn rate?
Monthly churn rate measures losses within a single month, while annualized churn rate projects what cumulative attrition would look like over 12 months if the monthly rate stayed constant, using the formula 1 − (1 − monthly churn)^12. A monthly churn rate of just 5% compounds to roughly 46% annualized churn — a stark reminder that small monthly leaks add up to losing nearly half your customer base in a year if left unaddressed.
What is considered a good churn rate?
For B2B SaaS companies, monthly churn under 1-2% (roughly 12-24% annualized) is generally considered healthy, while consumer subscription businesses often tolerate higher churn of 3-7% monthly given lower price points and switching costs. Enterprise software with long contracts often targets under 1% monthly. Benchmark against your specific industry and price tier rather than a single universal target, since churn tolerance varies enormously by business model.
How is average customer lifespan calculated from churn rate?
Average customer lifespan in months is approximately 1 divided by the monthly churn rate (expressed as a decimal), or equivalently 100 divided by the churn rate percentage. A 5% monthly churn rate implies an average lifespan of about 20 months, while a 2% monthly churn rate implies a much longer 50-month average lifespan. This figure feeds directly into customer lifetime value calculations.
How does churn rate affect revenue, not just customer count?
Multiplying customers lost by your average revenue per user (ARPU) converts churn into a concrete dollar figure — both a monthly revenue impact and, annualized, a yearly figure. This reframing often makes churn far more urgent to leadership than a percentage alone, since losing 30 customers at $50/month ARPU is $1,500 in monthly recurring revenue walking out the door, or $18,000 annually if the pattern continues unaddressed.
Should churn rate include downgrades, or only full cancellations?
This calculator measures customer (logo) churn — full account cancellations — rather than revenue churn, which also captures downgrades and reduced spending among customers who remain. Many SaaS businesses track both: logo churn shows how many accounts you are losing, while net revenue retention (which can exceed 100% with strong expansion revenue) shows the dollar impact including upgrades, downgrades, and cancellations combined.
Sources and References
- Bain & Company. "The Value of Online Customer Loyalty and How You Can Capture It."
- OpenView Partners. "SaaS Benchmarks Report" (annual churn benchmarks by company stage).
- Harvard Business Review. "The Value of Keeping the Right Customers."