Stockouts kill your organic rank and let competitors take your customers. Overstocking eats your cash and racks up long-term storage fees. This tool helps you find your reorder point — the exact inventory level at which you need to place your next PO.

The Formula

Metric	Formula
Safety Stock	Avg Daily Sales × Safety Buffer (days)
Reorder Point	(Avg Daily Sales × Lead Time in days) + Safety Stock
Days of Inventory Remaining	Current Inventory ÷ Avg Daily Sales

Worked Example

You sell 20 units/day, your supplier’s lead time (production + freight) is 45 days, you want a 14-day safety buffer, and you currently have 800 units in stock (including in-transit + at Amazon):

Input / Output	Value
Avg Daily Sales	20 units
Lead Time	45 days
Safety Buffer	14 days
Safety Stock	280 units
Reorder Point	1,180 units
Current Inventory	800 units
Days of Inventory Remaining	40 days
Status	Reorder now — current inventory (800) is already below the reorder point (1,180)

Quick Reference: Reorder Point by Lead Time

Assuming 20 units/day average sales and a 14-day safety buffer:

Lead Time	Safety Stock	Reorder Point
30 days	280 units	880 units
45 days	280 units	1,180 units
60 days	280 units	1,480 units
90 days	280 units	2,080 units

Tips

• Use your trailing 30–60 day sales velocity, not lifetime average — seasonality changes this fast.
• Lead time should include production time + freight + Amazon inbound processing, not just factory time.
• Watch your Inventory Performance Index (IPI) score — both stockouts and excess inventory hurt it.
• Increase your safety buffer around Q4 and any known supplier holidays (e.g. Chinese New Year).

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Want a full supply chain plan built around your actual lead times? We’ll map out your reorder points and PO calendar for the year.