A practical workflow
Follow the guide step by step
- 01
Start with a realistic selling price
Use the current listing price as a starting point, then consider whether your expected selling price needs to account for coupons, promotions, or competitive pressure.
- 02
Add marketplace costs
Include the category referral fee and an FBA fulfillment estimate based on product size and shipping weight. Verify dimensions and weight when the listing data is incomplete.
- 03
Enter your landed product cost
Add supplier cost plus inbound shipping and other per-unit costs you pay before the item is ready to sell.
- 04
Include operating assumptions
Account for advertising, expected returns, and discounts if they apply to your sourcing decision. Separate assumptions from verified costs.
- 05
Review profit, ROI, and downside
Check estimated profit per unit, margin, break-even price, and ROI. Then see how the estimate changes if the listing price falls.
Use estimates as a screening step
Fee calculators simplify a decision; they do not know every seller-specific cost or future marketplace change. Confirm the current fee category and fulfillment classification before ordering inventory.
Margin Seller calculates an estimate from supported visible listing details and costs you enter. It does not connect to Seller Central or guarantee a sale or profit.
A worked structure for the calculation
Write each cost on its own line so you can see which one moves the result. Use the same pack size on every line, so a case price is not compared with a single-unit sale.
After the base calculation, repeat it at a lower price and with a higher return rate to see how much room you have.
Use an FBA cost worksheet before you calculate
Write down the expected selling price, supplier cost per listing unit, inbound and preparation cost, marketplace and fulfillment estimates, advertising, discounts, storage over the expected hold period, and return-related assumptions. The per-unit estimate is only as complete as this list.
Verify the Amazon category, exact variation, dimensions, shipping weight, and fulfillment classification. When a listing omits a measurement or a product’s classification is uncertain, find a reliable source or measure it; do not let a convenient default stand in for evidence.
- Keep the supplier pack and marketplace listing pack on the same unit basis.
- Mark every value as observed, seller-entered, or still unverified.
- Use Review while a material measurement or category assumption remains unresolved.
Common questions
Frequently asked questions
What is the basic per-unit profit calculation?
Estimate revenue per unit minus product cost and all applicable per-unit marketplace, fulfillment, shipping, advertising, discount, and return-related costs.
Is ROI the same as profit margin?
No. ROI compares estimated profit with the cash invested in the unit; margin compares estimated profit with the selling price.
What is the formula for FBA profit?
Selling price minus supplier cost, referral fee, FBA fulfillment fee, storage, prep, inbound shipping, return allowance, and advertising. ROI is profit divided by supplier cost.
Ready to check a listing?
Put the assumptions to work.
Bring the visible listing facts and your own costs into a product audit before you commit to inventory.