ROI vs Margin: Two Numbers Sellers Often Mix Up
Return on investment and profit margin both turn up in seller reports, and they get swapped all the time. It's an easy mistake that can make a store look healthier than it is.
Our first US store, in numbers
In 2022, our first US store on Amazon recorded these figures over about three months:
- Product sales: $9,502
- Total invested: $5,570
- Net profit after product, shipping and operating costs: $1,780
Return on investment
ROI asks: what did the money I put in earn?
$1,780 ÷ $5,570 = 32%
Use ROI when you're deciding where to put capital. If you could spend the same $5,570 on two different products, ROI tells you which one worked harder.
Net margin
Margin asks: how much of each sales dollar did I keep?
$1,780 ÷ $9,502 = 18.7%
Use margin when you're judging pricing and costs. It shows how much room you have if fees rise, a competitor cuts prices, or you start paying for ads.
Why it matters
The same store has a 32% ROI and an 18.7% margin. Call the first number a margin and you'll think you have nearly twice the cushion you really have. That leads to bad decisions on ad budgets and discounts.
Three checks before you trust a number
- Check the base. Is it divided by money invested, or by sales?
- Check the costs. Does profit include marketplace fees, returns, ads and tools, or only the product cost?
- Check the time period. A strong holiday quarter tells you little about a normal month.
These numbers come from one store in one period. They're an example of the math, not a typical result.