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💰 Financial · Rex's Toolbox

Recurring Donor Program Calculator

Sustainer revenue, churn, and the value of converting one-time donors.

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Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.

Try a scenario

Click to load — tweak from there.

Inputs

Result

Net monthly revenue today

$8,424

Net monthly revenue at horizon

$12,120

Sustainers at horizon

460

Cumulative net revenue

$381,783

Lifetime value per sustainer

$752

Average months retained

28.6

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How to use this

  1. 1Enter current monthly donors.
  2. 2Enter average monthly gift ($).
  3. 3Enter new sustainers per month.
  4. 4Enter monthly churn (cancels + card failures) (%).
  5. 5Enter projection horizon (months).
  6. 6Enter processing fees (%).
  7. 7Read your net monthly revenue today on the right — it updates as you type.
  8. 8Hit Share to keep the scenario or send it to someone.

About this calculator

Recurring donors are worth several times a one-time giver because they renew by default. Model the program's monthly revenue, account for card failures and cancellations, and see what a conversion push is worth over three years.

FormulaMonthly revenue = sustainers × average gift; retained value = revenue ÷ monthly churn.

Worked example

Using the values the calculator loads with:

Inputs

  • Current monthly donors: 320
  • Average monthly gift: 27 $
  • New sustainers per month: 18
  • Monthly churn (cancels + card failures): 3.5 %
  • Projection horizon: 36 months
  • Processing fees: 2.5 %

Results

  • Net monthly revenue today: $8,424
  • Net monthly revenue at horizon: $12,120
  • Sustainers at horizon: 460
  • Cumulative net revenue: $381,783
  • Lifetime value per sustainer: $752
  • Average months retained: 28.6

What each field means

Inputs

Current monthly donors
The current monthly donors used in the calculation. Starts at 320 so you have a working example on load.
Average monthly gift ($)
The average monthly gift used in the calculation, measured in $. Starts at 27 $ so you have a working example on load.
New sustainers per month
The new sustainers per month used in the calculation. Starts at 18 so you have a working example on load.
Monthly churn (cancels + card failures) (%)
The monthly churn (cancels + card failures) used in the calculation, measured in %. Starts at 3.5 % so you have a working example on load. Accepted range: 0.1–25 %.
Projection horizon (months)
The projection horizon used in the calculation, measured in months. Starts at 36 months so you have a working example on load. Accepted range: 1–120 months.
Processing fees (%)
The processing fees used in the calculation, measured in %. Starts at 2.5 % so you have a working example on load. Accepted range: 0–10 %.

Results

Net monthly revenue today
Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Net monthly revenue at horizon
Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Sustainers at horizon
Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Cumulative net revenue
Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Lifetime value per sustainer
Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Average months retained
Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.

FAQ

How much of churn is involuntary?

Often a third to a half. Expired and reissued cards silently kill recurring gifts, which is why account updater services and a dunning email sequence usually pay for themselves within a quarter.

What ask amount converts best?

Framing around a unit of impact at $15–$35 per month converts far better than an open field. Anchoring too high suppresses starts, and starts compound while single large gifts do not.

Accuracy and limitations

  • Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
  • Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
  • This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.

Related tools

Donor Retention Rate Calculator

Retention rate, attrition cost, and the value of a retained donor.

Fundraising Goal Calculator

Turn a campaign goal into the gift pyramid and prospect count it requires.

Cite this calculator

Writing about this topic? Grab a citation — every link helps keep these tools free.

APA
RevenueLab. (2026). Monthly Giving Program Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/monthly-giving-program
HTML
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/monthly-giving-program" target="_blank" rel="noopener">Monthly Giving Program Calculator — RevenueLab</a> (2026).</p>
Markdown
Source: [Monthly Giving Program Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/monthly-giving-program) (2026).
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