The formula, the inputs, and the practical judgment calls that make reorder points actually work for wholesale distributors.
A reorder point is the inventory level at which you should place a new purchase order for an item. When on-hand stock drops to or below the reorder point, the system alerts the purchasing team that it is time to reorder. The concept is simple. Getting the number right for each of your hundreds or thousands of SKUs is where most distributors struggle, because the right reorder point depends on demand velocity, supplier lead time, and how much risk you are willing to accept for that specific item.
The standard reorder point formula is: Reorder Point = (Average Daily Demand × Lead Time in Days) + Safety Stock.
Average daily demand is how many units you sell or consume per day, calculated from recent history. Lead time is the number of days between placing a purchase order and receiving the goods. Safety stock is a buffer to protect against demand spikes or delivery delays. Each of these inputs requires judgment, not just calculation.
Use a recent window of actual sales data — typically the last 60 to 90 days. Shorter windows are more responsive to trends but more volatile. Longer windows are smoother but may miss recent shifts. For seasonal items, use the same period from the prior year rather than the trailing average.
The ERP should calculate this automatically from invoice line data. If you are calculating manually, sum the total quantity sold for the item over the period and divide by the number of days. For example, if you sold 600 units of item X over the last 90 days, average daily demand is 600 ÷ 90 = 6.7 units per day.
Lead time is not the number the vendor quotes. It is the actual, observed number of days from when you place the order to when the goods are received, counted, and available for sale. Most distributors find that actual lead times are longer and more variable than vendor quotes because of processing delays, shipping variability, and receiving backlogs on your end.
Track actual lead times by recording the PO date and the receipt date for each purchase order. Over time, you build a realistic lead time estimate per vendor per item. The ERP should track this automatically if it manages purchase orders and receiving. Use the average actual lead time, not the vendor's promised time, in your reorder point formula.
For critical items, use the worst-case lead time (the longest actual lead time you have observed) rather than the average. This protects against the delivery delay scenario that would hurt you most.
Safety stock is the buffer that protects you when demand is higher than average or delivery takes longer than expected. Setting it too low means stockouts. Setting it too high means excess capital tied up in inventory. The right level depends on how important the item is to your business and how costly a stockout would be.
A simple approach for most distributors: set safety stock equal to a fixed number of days of average demand, varied by the item's ABC classification.
Using the earlier example: if item X is an A item with average daily demand of 6.7 units, safety stock at 10 days would be 67 units.
Continuing the example: item X has average daily demand of 6.7 units, a vendor lead time of 5 days, and safety stock of 67 units (10 days). The reorder point is (6.7 × 5) + 67 = 33.5 + 67 = 100.5, rounded to 101 units. When on-hand stock reaches 101 units, the system generates a reorder alert.
The reorder quantity (how much to order) is a separate calculation that considers economic order quantity, vendor minimums, case pack sizes, and storage capacity. Most distributors start by ordering enough to bring stock back to a target level (reorder point + a defined replenishment quantity) and then refine from there.
Reorder points are not set-and-forget. Demand changes with seasons, customer acquisitions, customer losses, and market shifts. Lead times change with supplier performance, shipping disruptions, and logistics costs. Recalculate reorder points at least quarterly, and monthly for A items or items with volatile demand.
The ERP can automate this if it tracks sales velocity and actual lead times continuously. Ask the Ledger's reorder alert system compares on-hand stock against the reorder point and generates alerts when items need attention. The purchasing team reviews the alerts, adjusts quantities as needed, and converts approved reorders into purchase orders.
Reorder point management connects directly to purchasing workflow, cash flow management, and customer service levels. For more context on inventory management strategy, see How to Calculate Inventory Turnover, Inventory Management for Hardware Distributors, and Warehouse Management for Small Distributors.