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Reorder point formula: how to calculate when to reorder

Updated September 15, 2026

A reorder point is the stock level that should trigger a purchase order. Order when stock falls to it and, on an average week, the delivery arrives just as the safety stock starts being used.

The formula

Reorder point = average daily sales × lead time (days) + safety stock

  • Average daily sales: units sold per day over a recent window (30–90 days).
  • Lead time: days from placing the order to having sellable stock, including production, shipping, customs and receiving.
  • Safety stock: the buffer for demand spikes and late deliveries. See the safety stock guide.

Worked example

A candle sells 8 units a day. The supplier takes 25 days door to door. Safety stock is 60 units.

Reorder point = 8 × 25 + 60 = 260 units.

With 420 units on hand, you have (420 − 260) ÷ 8 = 20 days until you need to order.

Compare the reorder point with stock position, not stock on hand

Stock position = on hand + already ordered but not received. If 150 units are on the way, ordering again because on-hand stock hit 260 double-orders. Most spreadsheet reorder sheets make this mistake.

Four mistakes that make the number wrong

  1. Averaging over out-of-stock days. A product that sold 10 a day but was out of stock for 10 of the last 30 days shows an average of 6.7. Exclude days with zero stock.
  2. Using the quoted lead time. If the supplier quotes 30 days but the last three orders took 38, plan with 38.
  3. Ignoring trends. A 90-day average lags a product that is taking off. Weight recent weeks more heavily, but don't chase a single spike.
  4. Forgetting the order cycle. The reorder point says when. How much to order should cover lead time plus the time until your next order, plus safety stock, minus stock position.

How much to order

Order quantity = daily sales × (lead time + order cycle) + safety stock − stock position

Round up to the supplier's minimum order quantity and case pack.

Try it for one product with the reorder point calculator, or for your whole catalog with the free CSV reorder report.