THE NUMBERS, EXPLAINED
How to use this calculator.
A container is bought before the first refill and replaced after each full lifetime if more refills follow. All refills deliver the same number of uses.
Start with your inputs
Enter starter container cost, refill pack price, yield per refill (uses), container replacement interval (refills), refills to compare. Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Starter container cost | 12 |
| Refill pack price | 6 |
| Yield per refill (uses) | 20 |
| Container replacement interval (refills) | 5 |
| Refills to compare | 10 |
A worked example
With the example inputs above, containers purchased is 2. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Containers purchased | 2 |
| Total repeated-refill cost | 84 |
| Cost per delivered use | 0.42 |
How this is calculated
Containers purchased
Divide refill count by container lifetime and round up.
Total repeated-refill cost
Add container purchases and all refill costs.
Cost per delivered use
Divide total cost by refill count times delivered uses.
Symbols and units
- a
- Starter container cost
- b
- Refill pack price
- c
- Yield per refill (uses)
- d
- Container replacement interval (refills)
- e
- Refills to compare
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
A container is bought before the first refill and replaced after each full lifetime if more refills follow. All refills deliver the same number of uses.
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?
Containers purchased; Total repeated-refill cost; Cost per delivered use. 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: A container is bought before the first refill and replaced after each full lifetime if more refills follow. All refills deliver the same number of uses.
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 →