Inventory planning
Weeks of Supply Calculator
Estimate how many weeks current inventory can support at the current average weekly demand.
Formula / rule
Weeks of supply = usable inventory ÷ average weekly demandA calculation with the formula, input assumptions, interpreted result and practical next action.
What this calculator tells you
Estimate how many weeks current inventory can support at the current average weekly demand. The result is a planning signal, not a demand forecast. It is most useful when the input period and units match how the SKU is actually replenished.
Use consistent inputs
Keep demand, lead time, costs and inventory values in compatible units. A daily demand figure paired with a weekly lead time, or cost values mixed with selling prices, can produce a mathematically valid but operationally wrong result.
Interpret the result before acting
Compare the calculated value with recent stockouts, supplier delays, seasonality, promotions and minimum order quantities. If the result changes sharply because of one unusual period, investigate the data instead of automatically changing the replenishment policy.
Limitations
Simple inventory formulas assume the supplied averages and costs represent future conditions. Intermittent demand, highly seasonal products, perishability, capacity constraints and volatile supplier lead times may require a forecasting or optimization model rather than a single formula.
Use this result in a real workflow
Save the original input beside the result and record where the value will be used next—product master, label artwork, marketplace import, warehouse process or replenishment policy. The visible rule on this page is: Weeks of supply = usable inventory ÷ average weekly demand. If the destination system transforms leading zeros, units, dates or separators, correct that hand-off before processing the full catalog.
Planning result, not a forecast guarantee. Review seasonality, promotions, intermittent demand and supplier variability before acting.