Inventory Reorder Point Calculator

What is a Reorder Point?

Your reorder point is the inventory level at which you need to place a new purchase order so the replacement stock arrives before you sell out — accounting for how long your supplier takes to deliver, plus a safety buffer for demand spikes or shipping delays.

The formula

Reorder Point = (Average Daily Sales × Lead Time in Days) + Safety Stock. The first part covers expected sales during the time it takes a new order to arrive; the safety stock on top covers the unexpected — a sales spike, a delayed shipment, or a supplier hiccup.

How to use it

1. Enter your average daily sales rate (use recent, representative data, not a one-off spike day).
2. Enter your supplier's typical lead time, from placing the order to the stock arriving at Amazon's warehouse (include your own prep time too).
3. Set a safety stock buffer — a common starting point is 15–25% of your lead-time demand, though this depends on how variable your demand and lead times are.
4. Optionally enter your current inventory to see roughly how many days until you hit the reorder point.

Running out of stock on Amazon doesn't just cost you sales during the gap — it can also hurt your listing's search ranking and your account's Inventory Performance Index, both of which take time to recover after you're back in stock. Reordering a bit early is almost always cheaper than reordering too late.