Amazon max buy cost calculator
The most you can pay a supplier for a unit and still make your return. Enter the price it will sell for on Amazon, its category and packaged size, your shipping and prep costs and the ROI you want: the calculator takes off Amazon's referral and FBA fees and gives your max buy cost per unit and per case, for wholesale and online arbitrage.
| ROI | 20% | 30% | 50% | 100% |
|---|---|---|---|---|
| Pay at most | $12.19 | $11.25 | $9.75 | $7.31 |
Break-even: $14.63 a unit. Pay more than that and every sale loses money.
How the max buy cost is worked out
- What's left = selling price − Amazon's referral fee − the FBA fee − shipping to Amazon and prep − other costs.
- ROI = profit ÷ what the unit cost you (the price you paid plus any sales tax). For an ROI of R, the most you can pay is what's left ÷ (1 + R), and less the sales tax.
- Least profit: on cheap items a good ROI can still be a few cents a unit; the calculator takes the lower of the two limits.
In the example, a $24.99 kitchen item pays a $3.75 referral fee and a $5.61 FBA fee (large standard, charged on its dimensional weight), and $1.00 goes on shipping, prep and other costs. That leaves $14.63. For a 30% ROI, pay at most $14.63 ÷ 1.3 = $11.25: then each sale makes $3.38, a 13.5% margin. A case of 24 is worth at most $270.00.
From October 15 to January 14, Amazon charges its holiday peak FBA fees: the same item's fee is $5.93, so the most to pay drops to $11.00. Stock you buy now for the holidays sells at peak fees (see the holiday peak fee calculator).
ROI or margin?
ROI measures profit against the money you put in; margin measures it against the selling price. A reseller's money turns over with every shipment, so ROI tells you what your cash earns: a 30% ROI on stock that sells in a month earns far more in a year than the same ROI on stock that sits for six months. Pick the ROI that pays for your time, the money tied up and the risk, and ask more of items that sell slowly or whose price moves a lot.
Before you buy
- Use the price it will really sell for. Look at the price over the last few months, not today's lowest offer, and count the other sellers you'll share the sales with.
- Check the package. A box just over a weight or size break moves to a dearer FBA fee: the size tier calculator shows how close it is.
- Count storage and returns. Slow stock pays monthly storage and, after six months, the aged inventory surcharge (the storage fee calculator adds it up); some categories have high return rates.
- Check the category's referral rate at your price. Some categories charge less under $10 or $15: the referral fee calculator lists them.
Max buy cost questions
Does the calculator include the Professional plan?
No: the $39.99 a month doesn't change with each unit. Spread it over what you sell in a month and add it to other costs if you want it in.
Where does shipping to my prep center go?
In shipping to Amazon and prep, per unit, with the prep center's fees and the freight into Amazon.
How do I know what each batch really made?
Every buy is a batch with its own cost. MyProfit reads your supplier invoices and freight bills, follows the units into your FBA shipments, and gives every sale the cost of the batch it came from, first in, first out.
Fees: Amazon's 2026 US referral fees (Seller Central fee schedule) and FBA fulfillment fees with the 3.5% fuel and logistics surcharge, read October 2026. Amazon can change its fees at any time.
Know what every batch you buy really makes
MyProfit pulls your orders, fees, settlements, returns and ad spend from Amazon every night and shows your real profit by product, day and payout. 30 days of everything free, then $19.99 a month, or keep the free plan: it finds the money Amazon still owes you and checks your FBA fees, for good.