How to set a reorder point that doesn't sink you at Q4

A reorder point is just: how many units should be left on the shelf when you hit "order more"? Get it wrong and you either stock out during peak season or drown in storage fees on units that don't move.

The basic math

Reorder point = average daily sales × lead time in days, plus a safety buffer for the days your supplier is slow or a shipment gets stuck. If you sell 20 a day and it takes 30 days to land, you need 600 units in transit plus buffer before you hit zero.

The part people skip is the buffer. Lead times are averages. Real ones swing — a port backlog, a customs hold, a carrier that drops your pallet. A safety stock of one to two weeks of sales covers most of those without tying up too much cash.

The seasonality trap

June lead time and November lead time are not the same world. Freight books up, factories run double shifts, and everything takes longer. If you set your reorder point from summer numbers and apply it in October, you will stock out in the middle of Q4 — exactly when a day of lost Buy Box costs the most.

Build your Q4 reorder point from your Q4 daily sales (often 2–4× your baseline) and your worst observed lead time, not the average. It feels like you're ordering way too early. You are — and that's the point.

Chinese New Year

If your supplier is in China, the factory can shut for two to three weeks around late January or February. Shipments booked late don't move until it's over. Sellers who forget this place a January order that arrives in March, miss the window, and stall.

Plan the CNY gap into your lead time for any order placed in the month before. Add those weeks to the buffer so you're not relying on a factory that's closed.

The cost of getting it wrong

Stock out and you lose the sales plus the rank you spent months building — and rank is slow to come back. Over-order and you pay long-term storage fees on units sitting in Amazon's warehouse, which quietly eat the margin the product made. Use a reorder point calculator with your real Q4 numbers, set the order, and stop checking the inventory page every hour.