THE NUMBERS, EXPLAINED
How to use this calculator.
Assumes the account would otherwise contribute nothing and the recurring offer lasts through all retained months. No causal retention estimate is made.
Start with your inputs
Enter one-time retention offer cost (currency), normal monthly contribution per account (currency), monthly contribution reduction during offer (currency), assumed additional retained months. Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| One-time retention offer cost (currency) | 60 |
| Normal monthly contribution per account (currency) | 30 |
| Monthly contribution reduction during offer (currency) | 10 |
| Assumed additional retained months | 6 |
A worked example
With the example inputs above, monthly contribution after offer (currency) is 20. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Monthly contribution after offer (currency) | 20 |
| Break-even retained months | 3 |
| Whole retained months to recover offer | 3 |
| Scenario net retention contribution (currency) | 60 |
How this is calculated
Monthly contribution after offer (currency)
Deduct recurring offer cost from normal contribution.
Break-even retained months
Divide one-time offer cost by ongoing contribution after offer.
Whole retained months to recover offer
Round break-even time up to completed monthly periods.
Scenario net retention contribution (currency)
Accumulate retained monthly contribution and subtract initial offer cost.
Symbols and units
- a
- One-time retention offer cost (currency)
- b
- Normal monthly contribution per account (currency)
- c
- Monthly contribution reduction during offer (currency)
- d
- Assumed additional retained months
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Assumes the account would otherwise contribute nothing and the recurring offer lasts through all retained months. No causal retention estimate is made.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Monthly contribution after offer (currency); Break-even retained months; Whole retained months to recover offer; Scenario net retention contribution (currency). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Assumes the account would otherwise contribute nothing and the recurring offer lasts through all retained months. No causal retention estimate is made.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
OpenStax: Calculate a Break-Even Point in Units and Dollars ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
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