Donor Retention Calculator

This calculator quantifies what donor churn actually costs a nonprofit, and what fixing it is worth. Retention rate is simply the donors retained from last year divided by donors at the start of the year; churn rate is its complement. Lifetime value takes a different approach than a flat multi-year assumption: it models each donor's expected giving lifespan as a geometric series based on retention rate — expected lifetime years equals 1 divided by (1 minus the retention rate as a decimal) — so a donor pool with 60% retention is modeled as giving for an average of 2.5 years, while a 90%-retention pool is modeled at 10 years. That formula diverges as retention approaches 100%, and a 100-year cap only kicks in at exactly 100% retention (every donor retained); a rate just short of that, like 99.98%, still runs through the uncapped formula and can produce an expected lifetime of thousands of years. Treat any lifetime figure north of a few decades as a sign your donor pool is unusually small or retention is being entered as a rounded 100% rather than as evidence of a truly multi-generational donor base.

Lifetime value then multiplies that expected lifespan by the average gift amount. Lost revenue is the straightforward dollar value of gifts that walked away this year; replacement cost applies your acquisition cost per donor to however many lapsed, capturing the fact that replacing a lapsed donor isn't free. Net impact is the combined hit of lost revenue plus replacement cost, shown as a negative figure. Revenue gain models a specific what-if: retention improved by exactly 10 percentage points (capped at 100%), showing the added revenue from the donors that improvement would keep — useful for justifying investment in stewardship and donor-communications programs to a board that wants to see the payoff in dollars.