Reorder Point Calculator
Know exactly when to reorder stock.
Buffer units to cover demand spikes and delays.
Results update as you type.
How it works
The reorder point is the inventory level at which you should place a new order so that fresh stock arrives just before you run out. You calculate it by multiplying your average daily usage by the supplier lead time, then adding a safety-stock buffer. The result is a simple threshold: when your on-hand quantity drops to this number, it is time to reorder. This is one of the most useful tools in inventory management because it removes guesswork from replenishment. Without a reorder point, businesses tend to either reorder too early, tying up cash and warehouse space, or too late, hitting stockouts that cost sales and damage customer trust. The reorder point balances these risks by accounting for exactly how much you sell while you wait for a delivery. The lead-time demand portion, daily usage multiplied by lead time, covers normal sales during the wait. The safety stock cushions against the two things that go wrong in practice: demand running hotter than average and suppliers delivering later than promised. Store owners, warehouse managers and operations teams use this calculator to set reorder triggers for each product, to automate purchasing rules, and to keep shelves reliably stocked without overinvesting in inventory. Recalculate it whenever your sales rate or lead time changes, set the threshold in your inventory system, and let it fire consistently so restocking becomes a routine, data-driven decision rather than a scramble every time stock runs low.
reorder point = (daily usage × lead time) + safety stock
The formula has two parts. Daily usage multiplied by lead time gives lead-time demand, the quantity you expect to sell during the days it takes a new order to arrive, ensuring you can keep selling while you wait. Safety stock is then added as a buffer against demand spikes and supplier delays, so a bad week does not empty your shelves. Their sum is the on-hand level at which you should trigger a fresh purchase order.
Source:Standard inventory management formula (reorder point)
We review all our tools from time to time to ensure accuracy.
Worked example
How to use this calculator
- 1
Enter your values
Enter average daily usage and lead time.
- 2
Adjust the options
Adjust safety stock if they apply — sensible defaults are already set.
- 3
Read your result
Reorder point updates instantly as you type — no button to press.
Frequently asked questions
What is safety stock and how do I set it?
Safety stock is a buffer of extra units held to protect against demand that runs above average or suppliers who deliver late. A simple approach is to hold a few days of average sales as a cushion, while more precise methods use the variability of your demand and lead time to size it statistically. The right amount balances the cost of holding extra inventory against the cost of a stockout, so high-margin or hard-to-replace items usually justify a larger buffer.
How do I find my average daily usage?
Take your total unit sales over a recent, representative period and divide by the number of days in that period. A trailing thirty-day window works well for steady sellers, while seasonal products should be based on the relevant season rather than a flat annual average. Because the reorder point scales directly with this figure, keeping it current matters; recalculate whenever your sales trend shifts so your reorder trigger reflects real demand rather than stale numbers.
What happens if my lead time changes?
Lead time feeds directly into the reorder point, so a longer lead time raises the level at which you must reorder, and a shorter one lowers it. If a supplier becomes slower or less reliable, recalculate immediately and consider increasing safety stock to cover the added uncertainty. Ignoring a lengthening lead time is a common cause of stockouts, because your old threshold no longer leaves enough runway for the delivery to arrive before you sell out.
Should each product have its own reorder point?
Yes. Different products sell at different rates and often come from different suppliers with different lead times, so a single blanket threshold would leave some items overstocked and others prone to stockouts. Calculate a reorder point per product, or per SKU, using its own usage rate and lead time. Most inventory systems let you store a reorder point for each item and alert you automatically when stock falls to that level, making per-product triggers easy to manage at scale.
Does the reorder point include the stock in transit?
The reorder point is the trigger level for placing an order, so it deals with on-hand stock rather than units already on their way. Once you place an order, those incoming units become stock in transit and will replenish you after the lead time. The key is to reorder as soon as on-hand inventory reaches the reorder point and not to double-order simply because a shipment is pending, which is why tracking open purchase orders alongside on-hand levels is good practice.