Donor Retention Calculator
Keeping a Donor Costs Far Less Than Finding One
Acquiring a new donor typically costs several times more than retaining an existing one, which is why donor retention rate is treated as a leading indicator of fundraising health, not just a year-end statistic. A slipping retention rate quietly erodes the base a development office relies on, even while total dollars raised looks stable in the short term.
The Formula
Donor Attrition Rate = 100% − Retention Rate
Retention counts only donors from the prior year who gave again — new donors acquired this year aren't part of the denominator or numerator, which keeps the metric focused purely on how well the organization holds onto its existing base.
Where This Calculation Matters
- Diagnosing fundraising health — a falling retention rate often signals stewardship or communication gaps well before overall revenue drops.
- Budgeting for acquisition — low retention means more must be spent acquiring new donors each year just to stay flat, directly affecting next year's fundraising budget.
- Segmenting stewardship efforts — organizations often calculate retention separately by gift level or donor tenure to find where the biggest drop-off occurs.
- Board reporting — retention rate alongside dollars raised gives a fuller picture of program sustainability than revenue figures alone.
| Donors retained | Retention rate | Attrition rate |
|---|---|---|
| 380 | 38% | 62% |
| 420 | 42% | 58% |
| 450 | 45% | 55% |
The nonprofit sector average donor retention rate is typically around 40–45%, based on widely cited fundraising effectiveness studies — use it as a rough benchmark rather than a target specific to your organization's size or cause.
How to Use This Calculator
- Enter the number of donors who gave again this year (retained donors).
- Enter the total number of donors from the prior year.
- Select Calculate to get the retention rate and the corresponding attrition rate.
Related Calculations
Track overall supporter base growth with the Membership Growth Calculator, or see how retained and new donors together move you toward a fundraising target with the Annual Fund Goal Calculator.