Reorder Point Calculator
Free, no signup. For small manufacturers and D2C brands.
Your numbers
Don't know your safety stock? Estimate it
Estimate = (Max daily demand × Max lead time) − (Average daily demand × Average lead time)
How to calculate a reorder point with lead time
A reorder point is the inventory level that tells you when to place a replenishment order. This calculator uses the standard formula:
Reorder point = (average daily demand × lead time in days) + safety stock
For example, if a product uses 32 units per day, the supplier lead time is 21 days, and you keep 180 units of safety stock, lead time demand is 672 units and the reorder point is 852 units. Place the next order when available inventory reaches that level.
Using this calculator for manufacturing
For a finished product, use average daily sales as demand. For a raw material or component, use average daily production consumption instead. Lead time should cover the full time from issuing a purchase order until stock is received, inspected, and ready to use—not only the supplier's shipping estimate.
Small businesses can start with recent spreadsheet data and review their highest-volume items monthly. Recalculate whenever demand changes, a supplier extends lead time, or a seasonal peak approaches. The formula determines when to order; minimum order quantities and production batch sizes still determine how much to order.
Why include safety stock?
Lead time demand covers an average replenishment cycle. Safety stock adds a buffer for demand spikes, late deliveries, rejected materials, and other variation. If you do not know your buffer yet, open the estimator above and enter recent maximum demand and lead-time values. For the full method, read how to calculate reorder point and safety stock.
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Compare Inventory Systems →FAQ
What is a reorder point?
A reorder point is the inventory level that triggers a new purchase order. It covers the demand you expect during your supplier's lead time, plus a safety buffer so a late delivery or a demand spike doesn't cause a stockout.
How is a reorder point different from safety stock?
Safety stock is the buffer you hold against uncertainty. The reorder point is the trigger level: expected demand during lead time plus that safety stock. You reorder when inventory falls to the reorder point — the safety stock is what's left if everything goes wrong.
What if my demand is seasonal?
Use the average daily demand for the season you're planning, not the whole year. For strong seasonality, recalculate your reorder points before each peak season using recent sales data for the equivalent period.