ROI calculator
Free, no sign-up, runs in your browser.
ROI is the number that matters when your constraint is cash rather than shelf space — which is most sellers most of the time. It asks what each dollar you put into inventory comes back as. Two products with the same margin can have very different ROI, and the one that turns faster is usually the better business even when it looks worse on margin.
The formula
ROI = profit ÷ the cash tied up in the unit, which is the product cost plus inbound shipping plus any per-unit cost you pay up front — but not amortised overhead, which is not money spent on this unit.
A worked example
A $29.99 product that lands at $8.00, sold on Amazon FBA in Home & Kitchen, 10×6×3 inches and 20 ounces packed:
| Revenue kept | $29.99 |
|---|---|
| Total fees | $10.35 |
| Total costs | $10.00 |
| Profit per unit | $9.64 |
| Margin | 32.14% |
| Markup | 96.4% |
| ROI | 96.4% |
What to watch
- ROI per cycle is not ROI per year. A 25% return that repeats six times a year beats a 60% return that repeats once.
- Slow stock quietly lowers ROI twice: the cash is locked up longer and storage fees accumulate against it.
- Amazon pays on a fortnightly cycle, so your real cash cycle is longer than your sell-through suggests.
- When cash is the binding constraint, rank products by ROI and turn rate, not margin.
The trap
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Questions
What ROI should I aim for in retail arbitrage?
A common rule is 30% or better per cycle, and it exists because fees and returns reliably eat a chunk of a thinner one. The number matters less than the turn rate behind it: 30% six times a year is a very different business from 30% once.
Is ROI the same as margin?
No. Margin divides profit by the sale, ROI by the cash you had to commit. For a cheap product sold dear they diverge sharply, and ROI is the one that tells you how fast you can grow without borrowing.
Why does ROI exclude the subscription?
Because the subscription is not capital you put into this unit — you would pay it anyway. Including it would conflate a return on investment with a return on overhead.
Rates on this page are the published schedules as of 2025-01-15 and are applied by the same code the calculator runs. Marketplaces reprice — confirm against your own seller dashboard before setting a price.