THE NUMBERS, EXPLAINED
How to use this calculator.
One review today with no outstanding receipts; use the same product-unit basis for retail and service consumption.
Start with your inputs
Enter daily retail product sales by sku, daily service use by sku, replenishment lead times by sku (days), usable stock by sku, desired cover after delivery (days). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Daily retail product sales by SKU | 2,3 |
| Daily service use by SKU | 1,1 |
| Replenishment lead times by SKU (days) | 5,4 |
| Usable stock by SKU | 10,20 |
| Desired cover after delivery (days) | 2 |
A worked example
With the example inputs above, demand through lead time and cover is 21, 24. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Demand through lead time and cover | 21, 24 |
| Units to order by SKU | 11, 4 |
How this is calculated
Demand through lead time and cover
Combine retail and service use over lead time plus cover.
Units to order by SKU
Deduct usable stock and round positive requirements up.
Symbols and units
- a
- Daily retail product sales by SKU
- b
- Daily service use by SKU
- c
- Replenishment lead times by SKU (days)
- d
- Usable stock by SKU
- e
- Desired cover after delivery (days)
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
One review today with no outstanding receipts; use the same product-unit basis for retail and service consumption.
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?
Demand through lead time and cover; Units to order by SKU. 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: One review today with no outstanding receipts; use the same product-unit basis for retail and service consumption.
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: Describe and Identify Cost Drivers ↗
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 →