Inventory Reorder Calculator
Estimate when to reorder, how many units to buy and how many days of stock remain.
Enter your inventory details
Use a representative sales period and consistent units.
Current inventory
Supplier & stock targets
Safety stock is converted into units using average daily sales. Target coverage is the desired total inventory position after replenishment.
How the reorder point is calculated
Reorder point is expected demand during supplier lead time plus safety stock.
Reorder point = average daily sales × (lead time days + safety stock days)
Worked example
At 5 units sold per day, 14 days of lead time and 7 days of safety stock, the reorder point is 105 units. With 120 on hand, 40 incoming and 10 committed, inventory position is 150 units. A 45-day target is 225 units, so the suggested purchase is 75 units.
Use inventory position, not just shelf quantity
Inventory position includes sellable on-hand units plus confirmed incoming units, less units committed to customers. Exclude damaged or unsellable stock.
Planning limitations
This estimate does not forecast seasonality, promotions or sudden demand changes, and does not apply supplier minimums, case packs or cash-flow limits. Read Ecommerce Inventory Turnover and Landed Cost per Unit for related guidance.
Margenao provides an independent planning estimate. Recheck stock, open orders, supplier lead times and demand before purchasing.