THE NUMBERS, EXPLAINED
How to use this calculator.
Discounts apply to the supplied category spend without caps or exclusions. Break-even scale preserves this exact category mix.
Start with your inputs
Enter annual membership fee, annual spending by category, supplied discount by category (%). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Annual membership fee | 60 |
| Annual spending by category | 500,200 |
| Supplied discount by category (%) | 10,5 |
A worked example
With the example inputs above, annual gross savings is 60. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Annual gross savings | 60 |
| Net savings after fee | 0 |
| Break-even total spend at this mix | 700 |
How this is calculated
Annual gross savings
Multiply each category spend by its discount and add.
Net savings after fee
Subtract membership fee from discounts.
Break-even total spend at this mix
Scale total basket spend until discounts equal the fee.
Symbols and units
- a
- Annual membership fee
- b
- Annual spending by category
- c
- Supplied discount by category (%)
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
Discounts apply to the supplied category spend without caps or exclusions. Break-even scale preserves this exact category mix.
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?
Annual gross savings; Net savings after fee; Break-even total spend at this mix. 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: Discounts apply to the supplied category spend without caps or exclusions. Break-even scale preserves this exact category mix.
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: Solve proportions and their applications ↗
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.
Read the quality report →