Free FBA reorder calculator
Enter your sales, stock and lead time. Get how many units to reorder, the date to order by, and the date you will run out. It runs in your browser. Nothing is sent anywhere.
Your result
- Average sales per week
- 30.0
- units
- Weeks of cover now
- 3.7
- weeks on hand, 5.7 with inbound
- Reorder quantity
- 154
- units
- Reorder point
- 180
- units (order when stock + inbound falls here)
Reorder by: today. You are at or below the reorder point.
Run-out date: …
How it works out the numbers
Average sales per week is units sold divided by the number of weeks. Weeks of cover is your stock divided by that average.
Reorder quantity = average sales per week × (lead time + target cover) × (1 + safety %), minus stock on hand and inbound. The reorder point is average sales per week × lead time × (1 + safety %). When stock plus inbound falls to that level, you order.
The run-out date counts stock on hand plus inbound, at today's sales speed, and assumes the inbound is sellable in time. The reorder-by date is when your stock plus inbound will reach the reorder point.
Use it well
Use shipped units, not orders, and leave out weeks when you were out of stock. Count lead time from the day you decide to order to the day the stock is sellable at Amazon. If you sell a product on a sale event, plan that separately.
Read the full method in how to calculate reorder quantity for Amazon FBA, and see what a stock-out really costs.
Next step
One product is easy. Hundreds are not.
This calculator does one product at a time. Our stock system does every product, every day, with your team's approval before anything is ordered.
Tell us how you plan stock today.
A free 30-minute teardown: how you plan reorders today, where your stock-outs come from, and a fixed price for fixing it.