The pre-filled numbers are example inputs, not averages or benchmarks. Replace them with your own.
Estimate
What moves the total
| Scenario | Collected | Net | Change |
|---|---|---|---|
| Your inputs | $11,250 | $10,313 | — |
| +10 points share of readers with a donor | $13,500 | $12,495 | +$2,183 |
| +1 donor per active reader | $15,000 | $13,950 | +$3,638 |
| +$5 average flat gift | $13,500 | $12,495 | +$2,183 |
| All three together | $21,600 | $20,352 | +$10,040 |
Math: 300 readers × 50% × 3 donors × $25 pledged each = $11,250 collected.
This calculator turns your own assumptions into an estimate of what a read-a-thon will collect and keep. It has two tabs. Estimate what we'll raise works forward from your readers to a dollar total. How many readers for our goal? works backward from the net amount you need. Every pre-filled number is an example input to replace with your own.
How the calculator works
The estimate is four numbers multiplied together, then adjusted for collection, fees and costs:
- Readers with a donor = Readers × Share of readers with a donor.
- Donors = Readers with a donor × Donors per active reader.
- Pledged = Donors × the amount pledged per donor (which depends on how donors give, below).
- Collected = Donors × (flat part + per-minute part × Per-minute pledges collected). Flat gifts are counted in full because they are paid when pledged. Only the per-minute part is reduced by the collection rate.
- Net = Collected − (Collected × Processing fees) − Fixed costs.
The results panel shows estimated collected, net after fees and costs, readers with a donor, donors, pledged per donor and collected per reader across all readers, not only those with donors. When some pledges are assumed unpaid, a line tells you how much of the pledged total is uncollected. A "Math:" line underneath spells out the multiplication with your numbers.
Three ways donors give
The How donors give menu changes which fields appear.
- Flat gift. Each donor gives the Average flat gift. Nothing depends on minutes, and the collection rate does not apply.
- Per minute read. Each donor owes Pledge per minute × Minutes per reader, limited by Cap per donor. A cap of 0 means no cap. The whole amount is billed after the event, so the collection rate applies to all of it.
- Mix of both. Donors giving flat sets the percentage who give a flat gift. The rest pledge per minute. The calculator blends the two into one average pledge per donor.
The cap
A cap is the most a per-minute donor can owe. The calculator uses whichever is smaller: rate × minutes, or the cap. Arithmetic At 5¢ a minute and a $20 cap, a reader who logs 300 minutes produces $0.05 × 300 = $15, under the cap. At 600 minutes the pledge would be $30, so the donor owes the $20 cap. The cap is reached at $20 ÷ $0.05 = 400 minutes, which is why it suits a 400-minute reading goal. Caps make per-minute pledges predictable for donors, which is why our guide to read-a-thon pledges recommends always offering one.
The collection rate
Per-minute pledges are billed after reading ends, when the final minutes are known. Some of those bills never get paid: a supporter forgets, an email goes to spam, or a family doesn't follow up. Per-minute pledges collected is your assumption about what share actually arrives. It is not a measured rate. We know of no published figure, so set it from your own past events. If you have none, try a few values and see how much the total moves. Collecting per-minute pledges up front with a cap removes most of this risk.
What moves the total
Below the estimate, a table changes one lever at a time and shows the new collected total, net and change in net:
- +10 points on the share of readers with a donor
- +1 donor per active reader
- +$5 on the average flat gift (flat and mixed modes) or +5¢ on the per-minute rate (per-minute mode)
- All three together
Use it to decide where to spend volunteer effort. The steps are not the same size: +1 donor on a base of 3 is a 33% increase, while +$5 on a $25 gift is 20%. Because the four numbers multiply, an equal percentage gain on any lever moves the total by the same percentage. The table shows what each realistic step is worth with your numbers.
One quirk worth knowing: if your cap is already binding, a higher per-minute rate changes nothing, and the table will show $0.
Goal mode
The second tab adds a Net goal field. The calculator finds the net each active reader brings in after fees, then divides: (Net goal + Fixed costs) ÷ net per active reader = readers with a donor needed, rounded up. Dividing that by your share of readers with a donor gives total readers needed. It also shows the share of your enrolled readers who would need a donor, and tells you whether the goal fits within your enrollment.
Choosing your inputs
| Input | What it means | Where to get it |
|---|---|---|
| Readers | Everyone invited to take part | Enrollment, or your program's sign-in count |
| Share of readers with a donor | Readers who get at least one supporter | Your last pledge-based event; if none, test several values |
| Donors per active reader | Average supporters per reader who has any | Last year's donor count ÷ readers with donors |
| Average flat gift | Typical flat amount per donor | Your past gift records, or the amounts on your pledge menu |
| Pledge per minute | Rate per minute, in dollars (0.05 = 5¢) | The rate you will suggest on the pledge sheet |
| Minutes per reader | Total minutes a typical active reader logs over the whole event | Last year's logs; or a daily goal × reading days |
| Cap per donor | Most a per-minute donor can owe | Your pledge sheet |
| Donors giving flat | Mixed mode only: share choosing a flat gift | Past records; otherwise try 50–70% |
| Per-minute pledges collected | Share of after-event pledges actually paid | Your own past collection; it is an assumption |
| Processing fees | All-in percentage your payment provider keeps | Ask your provider; use 0 for cash and checks |
| Fixed costs | Prizes, printing, celebration supplies | Your approved budget |
The fees field is a single percentage. If your provider also charges a fixed amount per gift, small gifts lose a larger share, so ask for both numbers and use an all-in percentage that reflects your expected gift sizes.
Fixed costs are the one input you fully control. Decide the recognition budget before launch and keep it small. Our page on read-a-thon prizes and incentives has low-cost and free recognition ideas that reward reading rather than dollars.
Worked example
Example An example school with 400 readers. Half get at least one donor, and each of those reaches 3 donors. Donors give in a mix: 60% give a flat $25, and 40% pledge 5¢ per minute capped at $20. The typical active reader logs 500 minutes. The organizers assume 90% of per-minute pledges get collected, fees of 3% and $600 in fixed costs.
- Readers with a donor: 400 × 50% = 200.
- Donors: 200 × 3 = 600.
- Per-minute pledge: $0.05 × 500 = $25, which is over the $20 cap, so each per-minute donor owes $20.
- Pledged per donor (blended): $25 × 60% + $20 × 40% = $15 + $8 = $23.
- Pledged in total: 600 × $23 = $13,800.
- Collected per donor: $15 + ($8 × 90%) = $15 + $7.20 = $22.20.
- Collected in total: 600 × $22.20 = $13,320. That leaves $13,800 − $13,320 = $480 assumed uncollected.
- Fees: $13,320 × 3% = $399.60.
- Net: $13,320 − $399.60 − $600 = $12,320.40, shown as $12,320.
Collected per reader across all 400 readers is $13,320 ÷ 400 = $33.30.
The "What moves the total" table for these inputs shows these changes to net:
- +10 points on share with a donor: +$2,584
- +1 donor per active reader: +$4,307
- +$5 on the flat gift: +$1,746
- All three together: +$10,546
In goal mode with a net goal of $10,000, each active reader brings in $13,320 ÷ 200 × (1 − 3%) = $64.60 after fees. ($10,000 + $600) ÷ $64.60 = 164.1, rounded up to 165 readers with a donor. At a 50% share that means 330 readers, and 165 ÷ 400 = 41.25%, shown as 42%. The goal fits within the 400 readers.
Method note: This calculator does arithmetic on your inputs. It does not contain benchmarks, averages or data from other events. The pre-filled values and the worked example are illustrations chosen to make the math easy to follow. We found no independent, method-disclosed benchmark for what read-a-thons raise. Documented results and their limits are on our read-a-thon economics page.
Why the planning report may show a different number. This calculator asks for the typical reader's minutes and the cap directly. The planning report generator works them out from your comfortable daily minutes, so with 15 minutes a day for two weeks it uses 210 minutes and a $10 cap rather than this example's 500 minutes and $20 cap. Enter the same inputs in both, including minutes, cap, readers and costs, and the two agree to the cent.
Privacy
The calculator runs entirely in your browser. Nothing you type is saved, sent to us or shared with anyone. Refreshing the page resets it to the example inputs.
Next steps
- Put this estimate into a complete printable plan with timeline, budget, roles and print list.
- Compare flat, per-minute, capped and per-book pledges for one donor, or a read-a-thon against a product sale, in the fundraising model comparison calculator.
- Choose a pledge structure and suggested amounts with our per-minute, per-book and flat pledge guide.
- See what documented events reported in our look at read-a-thon fundraising economics.
- Plan the whole event from approval to thank-yous with our read-a-thon fundraiser guide.
Frequently asked questions
Why does the collection rate only apply to per-minute pledges?
Flat gifts are usually paid when the donor makes the pledge, so the money is already in hand. Per-minute pledges can't be paid until the reader's final minutes are known, which means someone has to send a bill after the event. That second step is where some pledges are lost. If your flat gifts are also collected after the event, lower your average flat gift input to reflect the share you expect to receive.
What should I use for minutes per reader?
Use the total minutes a typical reader who has supporters logs over the whole event, not per day. If you have last year's logs, take the middle value, not the highest. If you don't, multiply a realistic daily amount by the number of reading days. For example, 25 minutes a day over 14 days is 25 × 14 = 350 minutes. Test a lower number too.
Can the net come out negative?
Yes. If fixed costs are larger than what you collect after fees, the net shows as a negative number. That usually means the prize or celebration budget is too large for the size of the event, or the share of readers with donors is set very low. Lower the costs or look at the scenario table to see which lever closes the gap.
Does the calculator include matching gifts from employers?
No. Employer matches arrive on their own schedule and depend on each donor's employer, so they are left out of the estimate. If you know roughly how much matching you received in past years, add it to your goal separately instead of raising the average gift. Remind donors to ask whether their employer matches gifts.