Free Startup Finance Tool
Churn Rate Calculator
Find your customer churn rate, retention rate, and average customer lifespan in seconds — and see how your retention stacks up. Free, private, no sign-up.
- Instant results
- 100% private
- Retention & lifespan
Your numbers
Email me this report
Get your churn, retention, and lifespan snapshot in your inbox to share with your team or investors.
The number that sets every other number
Churn quietly decides everything else. It sets your average customer lifetime, which sets your LTV, which sets what you can afford to spend acquiring anyone.
Enter customers and revenue lost over a period. You get both churn figures and the gap between them, which is usually where the story is.
What belongs in the denominator
Customer churn = customers lost ÷ customers at the start of the period. The common mistake is including customers you won during the period, which dilutes the rate and makes churn look lower than it is — particularly during a growth month, when you most need the real figure.
- Customers you started the period with are the only figure that belongs on the bottom of the fraction.
- Customers you won during the period are left out entirely.
- Customers you lost during the period are the numerator, whenever they joined.
A monthly figure compounds
This is the part that surprises people. A number that sounds survivable monthly is a very different number across a year, because each month takes its cut of what is left.
- 5% monthly churn is roughly 46% annually — you replace nearly half your customer base each year simply to stay level.
- Which means acquisition has to run at that pace before any growth happens at all.
- Halving monthly churn does far more for the business than almost any acquisition improvement of the same effort.
Customer churn versus revenue churn
These can point in opposite directions, and the gap between them is the interesting part. Track both — either one alone can look acceptable while the business has a real problem.
- Revenue churn = MRR lost ÷ MRR at the start of the period.
- Losing many small customers shows up badly in customer churn and barely in revenue churn.
- Losing one large customer does the reverse, and is usually the more urgent of the two.
Negative churn is the goal
When expansion revenue from existing customers exceeds the revenue lost to cancellations, your revenue grows without a single new customer. That is what net revenue retention above 100% describes, and it is the strongest position a subscription business can be in.
- It makes acquisition a growth lever rather than a treadmill.
- It is reached through upgrades, seats and usage, not through harder retention alone.
- The MRR and ARR Calculator breaks the movement down month by month.
Four numbers worth keeping
Why Parix.ai gives this away
We build subscription products, and churn is the number every one of those projects eventually turns on. These tools are the same checks we run for clients, put on a public page — which is why there is no paywall and no sign-up.
Calculate my churnWho uses it
Customer success teams tracking whether retention work is landing. Founders who need the figure before an LTV calculation means anything. Investors reading a subscription business from the outside.
It feeds these
Churn sets lifetime, so the LTV Calculator and the CAC Calculator are only as good as the figure you put in here.
When retention is the product problem
Most churn is decided in the first fortnight of use, not at the cancellation screen. Our product team works on that end of it.