By Rob Fogarty, Amazon FBA seller (OA and wholesale) and founder of Opero3P · October 2026
Your profit per unit is only as good as your cost per unit, and most sellers' cost is missing something. The most common gap is freight.
What landed cost actually is
Landed cost per unit is everything it took to get one sellable unit into Amazon:
- what you paid the supplier,
- freight to you or your prep center,
- prep and packaging,
- inbound shipping to Amazon.
Leave any of these out and every margin, every ROI and every repricer floor built on it is too optimistic.
The freight problem
A purchase order with ten products usually comes with one freight bill. How you split that bill across the products changes each one's cost. There are three sensible ways:
| Split by | How it works | Best for |
|---|---|---|
| Units | Each unit carries an equal share | Similar-sized products, or when you don't track weights |
| Value | Each line carries a share in proportion to what you paid for it | Small, expensive products mixed with cheap ones |
| Weight | Each line carries a share in proportion to its shipping weight | Mixed loads where some products are much heavier |
An example: a $200 freight bill on 100 phone cases and 20 cast-iron pans. Split by units, each case and each pan carries $1.67. But the pans are most of the weight, and most of the reason the bill is $200. Split by weight, the pans carry most of it and the cases almost nothing. Split by units, the cases look less profitable than they are and the pans look more profitable than they are. Your repricer will then defend the wrong floors.
A mistake I found in my own software
Opero3P has offered all three splits for a while. This week I found that orders set to split by weight were quietly being split by units: the weight look-up was matching products the wrong way, missed every time, and fell back without saying so. It's fixed now, and there's an automated check that the app and the server always calculate it the same way. If a weight is missing on any line, it now falls back to units and tells you, rather than skewing the split silently.
Use the cost of the units you hold
If you've bought the same product three times at three prices, the right cost is the one for the units you still have on hand, not the latest invoice or a number typed in months ago. That's what your floor should come from, too.
FAQ
What is landed cost for Amazon FBA? Everything it took to get one sellable unit into Amazon: supplier price, freight, prep and packaging, and inbound shipping.
Should I split freight by units or by weight? By weight when products differ a lot in weight and you have the weights. By units when they're similar or you don't track weight. By value when small expensive items ship with cheap ones.
Why does landed cost matter for repricing? Because the repricer's floor should come from it. A floor built on a cost that's missing freight lets the repricer sell at a loss.
Opero3P is my company.