Know your numbers before you buy. Enter a sale price, unit cost, and (optionally) fees to instantly see ROI, profit margin, net profit, and the maximum buy cost that still hits your target return.
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Profitability
Est. Amazon fees$7.83
Net profit / unit$13.16
ROI146.2%
Profit margin43.9%
Max buy cost @ target ROI$17.05
ROI = net profit ÷ unit cost. Margin = net profit ÷ sale price. The max buy cost is the highest price you can pay per unit and still hit your target ROI. Fees are estimated when no override is provided.
Fees, profit, ROI, sales estimates, scores and risk flags are automated estimates — not financial, business, or legal advice. Always verify in Amazon Seller Central before buying stock. Full disclaimer
Hit your ROI target on every product
Set a minimum ROI once and let Gridwinner flag every winning product across your entire supplier list.
ROIanswers “how much does each dollar I invest return?” It's net profit divided by your cost of goods. Most wholesale and arbitrage sellers set a minimum ROI (often 30%+) so their capital recycles quickly. Profit marginanswers “what share of the sale price do I keep?” That's net profit divided by sale price. Healthy listings usually clear both bars.
The max buy cost turns your target ROI into a hard negotiating number: the most you can pay per unit and still earn your required return. Walk into supplier conversations with that ceiling in hand.
Frequently asked questions
How is Amazon FBA ROI calculated?
ROI (return on investment) is your net profit divided by your unit cost, expressed as a percentage. If a product costs you $10 and nets $4 after fees, your ROI is 40%. ROI focuses on how hard your cash is working, which is why sourcing decisions usually target a minimum ROI.
What is the difference between ROI and profit margin?
ROI divides net profit by your cost (return on the money you spend). Profit margin divides net profit by the sale price (the share of revenue you keep). A product can have a high ROI but a thin margin, or vice versa. This tool shows both so you can judge the trade-off.
What does 'max buy cost' mean?
It is the highest price you can pay per unit and still achieve your target ROI, given the sale price and fees. Use it as your ceiling when negotiating with a wholesale supplier; if their price is above it, the deal won't hit your return goal.
How are the fees estimated?
If you leave the fee field blank, the tool estimates Amazon fees from the sale price and weight (15% referral plus an FBA size-tier fee). You can override it with your own figure, for example a value pulled from the Gridwinner app or Amazon's revenue calculator.