Profit, return and margin for resellers: the sums, with a worked example
Three numbers tell you whether a flip was worth it. They are easy to mix up, and mixing them up is how people think they made money when they did not.
Checked on 14 November 2026.
Profit: what is left
Profit is the sale price, minus everything the sale cost you, minus everything the item cost you.
What you keep from the sale = sale price − seller fee − shipping you pay to the buyer.
What the item cost = buy price + shipping you paid to get it.
Profit = what you keep − what the item cost.
Example: you buy trainers for 45 with 4 shipping. You sell them for 90 on a marketplace that takes 10%, and pay 4 to post them. You keep 90 − 9 − 4 = 77. The item cost 45 + 4 = 49. Profit: 77 − 49 = 28.
Return: profit against what you put in
Return on cost = profit ÷ what the item cost.
In the example: 28 ÷ 49 = 57%. For every 1 you put in, you got 0.57 on top. Return tells you how hard your money worked. A flip with 5 profit on a cost of 5 is a 100% return; 5 profit on a cost of 100 is 5%.
Margin: profit against the sale price
Margin = profit ÷ sale price.
In the example: 28 ÷ 90 = 31%. Margin tells you how much of each sale is yours. It is always smaller than the return on the same flip, which is why the two must not be confused.
The costs people forget
A sum is only as good as what goes into it. These are left out most often:
- The fee where you sell, including any payment fee on top.
- Shipping in both directions.
- Packaging.
- Returns: some of what you sell comes back.
- Tax, where you owe it. That depends on your country; ask an accountant, not a calculator.
- Your time. A flip that earns 5 and takes an hour is a job that pays 5 an hour.