Examples
Examples
Try the starting example
- Donors choosing the upgrade
- 5
- Old monthly gift ($)
- 10
- New monthly gift ($)
- 15
- Supplied monthly retention of upgraded donors (%)
- 90
- Months in incremental scenario, at most 120
- 3
- One-off upgrade campaign cash cost ($)
- 20
- Incremental expected gifts by month ($)
- M1: 25.00; M2: 22.50; M3: 20.25
- Total incremental expected gifts ($)
- $67.75
- Campaign cost ($)
- $20.00
- Incremental gifts less campaign cost ($)
- $47.75
Try another scenario
- Donors choosing the upgrade
- 5
- Old monthly gift ($)
- 10
- New monthly gift ($)
- 15
- Supplied monthly retention of upgraded donors (%)
- 100
- Months in incremental scenario, at most 120
- 3
- One-off upgrade campaign cash cost ($)
- 20
- Incremental expected gifts by month ($)
- M1: 25.00; M2: 25.00; M3: 25.00
- Total incremental expected gifts ($)
- $75.00
- Campaign cost ($)
- $20.00
- Incremental gifts less campaign cost ($)
- $55.00
Calculation method
Calculation method
Incremental expected gifts by month ($)
For month t starting at 1, donor count×(new−old gift)×retention^(t−1), rounded to US cents. The first month retains the full entered upgrade cohort.
Total incremental expected gifts ($)
Sum monthly incremental amounts.
Campaign cost ($)
Entered one-off cost.
Incremental gifts less campaign cost ($)
Incremental total−campaign cash cost.
Symbols and units
- a
- Donors choosing the upgrade
- b
- Old monthly gift ($)
- c
- New monthly gift ($)
- d
- Supplied monthly retention of upgraded donors (%)
- e
- Months in incremental scenario, at most 120
- f
- One-off upgrade campaign cash cost ($)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions & limits
Assumptions & limits
- An incremental cohort scenario under a supplied retention rate, not a donor forecast or a claim that an upgrade campaign causes the assumed conversions.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
Charity Commission: funds and reserves background; no universal reserve target ↗
Background reading; this does not imply endorsement or independent review of SumFizz.