Use the demand expected during the lead time, not just last month's.
Production, freight, customs, prep and Amazon receiving, not just factory time.
Days of extra demand you want covered. Enter 0 for none.
Available + usable reserved + inbound likely to arrive in time.
The formula
Reorder point = (average daily demand × lead time in days) + safety stock, where safety stock = daily demand × safety days.
- Use the full lead time: production, quality check, freight, customs, prep, Amazon receiving and transfer. Counting only factory time makes you reorder too late.
- Compare the reorder point with inventory position (available plus usable reserved plus inbound likely to arrive in time), not only available FBA units.
- For seasonal products, use the demand expected during the lead time, not the demand from the quiet month when you place the order.
- This gives when to order, not how much. Reorder quantity depends on target days of cover, supplier minimums, cash and aging risk.
Frequently asked questions
How do I calculate an Amazon FBA reorder point?
Reorder point equals average daily demand multiplied by the full lead time in days, plus safety stock. For example, 12 units a day with a 45-day lead time and 15 safety days gives 540 + 180 = 720 units.
What counts as lead time for FBA replenishment?
Everything between placing the purchase order and the units becoming available for sale: production, quality check, freight, customs, 3PL handling, and Amazon receiving and transfer time. Many sellers only count production time and reorder weeks too late.
How much safety stock should I hold?
The simple method is average daily demand times a number of safety days, which suits most small sellers. More advanced methods use demand and lead-time variation. The goal is a buffer that reflects real uncertainty without overstocking every SKU.
Go deeper
- Amazon FBA Reorder Point Formula Explained
Reorder point equals daily demand times lead time plus safety stock. Lead time includes freight, customs, prep, and Amazon receiving, not just factory time.
- Days of Inventory for Amazon Sellers Explained
Stock level shows how many units you have, but days of inventory shows how much time you have left. Here is the formula and the right sales window to use.
- Amazon Sales Velocity: A Formula for Inventory Decisions
Sales velocity equals units sold divided by days in the period, though the window you pick and how you handle stockout days can change the number substantially.
EcomSanity tracks sales velocity and days of stock per ASIN, so you can see which listings are approaching their reorder point.
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