Quick guide
How to use this calculator
- Gather Units on hand, and Average weekly demand for the same business scenario before calculating.
- Keep units and time bases aligned: daily demand needs lead time in days, and item costs must match the quantity represented by one inventory unit.
- Apply the displayed weeks of supply result to the stated decision only after checking every entered assumption.
Calculation method
Calculation method
Weeks of supply = Units on hand ÷ Average weekly demand.
The calculation uses these named inputs: Units on hand, and Average weekly demand. No market rate, benchmark, tax rule, or accounting classification is inserted automatically.
Fixed-decimal arithmetic remains exact through display unless a result is explicitly labelled approximate, such as a square-root inventory quantity.
Inventory planning and replenishment
Where the Weeks of Supply Calculator helps
Estimate how many weeks current stock covers at an entered weekly demand rate.
Use the result to translate entered demand, lead time, order cost, holding cost, and service assumptions into a planning quantity or interval.
- Prepare a purchase-order scenario
- Stress-test a supplier lead-time change
- Compare ordering and holding-cost assumptions
Interpretation check
How to audit the result
Recalculate the scenario when any of these inputs changes: Units on hand, and Average weekly demand.
Keep this formula beside the result: Weeks of supply = Units on hand ÷ Average weekly demand. Then compare the output with the source records and the calculator-specific assumption below.
- Confirm that all amounts use one currency and reporting period.
- Check that rates, counts, and quantities describe the same population or transaction set.
- Save the entered assumptions with the decision; the result alone is not reproducible evidence.
Worked example
Worked example
Using units on hand of 300 and average weekly demand of 1,200 gives 0.25.
Weeks of supply = Units on hand ÷ Average weekly demand.
Supported inputs
Precision and limits
Visible input limits
Fixed decimals accept up to 30 digits and 12 decimal places and are capped at an absolute value of 1e12 per input. Rates are capped at 1000%; percentage shares and method-specific domains may be narrower.
International scope
No currency, tax jurisdiction, accounting framework, payroll rule, marketplace fee schedule, financing term, or industry benchmark is selected automatically.
Decision boundary
Use the result to translate entered demand, lead time, order cost, holding cost, and service assumptions into a planning quantity or interval. Results remain arithmetic scenarios, not accounting records, forecasts, valuations, legal interpretations, professional advice, or recommendations.
Calculator-specific assumptions
This is a scenario from visitor-entered values. Keep currencies, periods, accounting classifications, and operating definitions consistent. It is not accounting, tax, legal, investment, or business advice.