Churn Rate Calculator 🔒 Your data never leaves your browser.

About this tool

Churn rate is the percentage of customers you lost during a period, and retention rate is its mirror image — the percentage you kept. The two numbers always add up to 100%, since every customer at the start of the period either stayed or left. Subscription and SaaS businesses usually track churn monthly, to catch problems quickly, or annually, to see the bigger picture; either way the formula is the same: customers lost ÷ customers at the start of the period × 100. Enter your own numbers above and both rates update instantly.

Small differences in monthly churn compound fast over a year, which is why they matter more than they first appear to. Take a steady 5% monthly churn: it’s tempting to assume the annual damage is simply 5% × 12 = 60%, but that overstates things, because each month’s 5% is taken from a shrinking customer base, not the original one. The accurate figure comes from (1 − 0.05)^12 ≈ 0.54 — meaning roughly 54% of the starting customers are still around after a year, so about 46% have churned. That’s lower than the naive 60% guess, but it still means replacing nearly half your customer base every single year just to stand still, which is exactly why shaving even a couple of points off a churn rate is worth far more over time than the percentage alone suggests. Everything here runs locally in your browser — no numbers are sent anywhere.

Frequently asked questions