How to fill it in
The example numbers are made up, not one of our products. Overwrite them with yours. Every field takes a per-unit dollar amount or a share of sales.
- Landed cost is the one people get wrong most. It's not the factory price. It's the factory price plus freight, duty and customs brokerage, divided by units.
- Referral fee is 15% in most categories, with a $0.30 minimum per item. A few categories are tiered by price. Our FBA fees guide covers the exceptions.
- FBA fulfillment fee depends on size, weight and price. Use the figure from Seller Central's Fee Preview report, or run the product through Amazon's free Revenue Calculator first. Since 17 April 2026 Amazon adds a 3.5% fuel and logistics surcharge; if your figure leaves it out, multiply by 1.035.
- Storage per unit is a month's storage bill divided by units sold that month, not units stored. A slow seller with a big footprint should show a high number here.
- TACoS is total ad spend divided by total sales, ads and organic together. It's the right ad number for per-unit profit because it spreads ad cost across every unit you sell. Not launched yet? Plan for more than you think. Ours runs about 12.5% on an established store.
- Refund rate is treated as lost revenue. That's conservative, because some returns go back on sale. If most of yours do, enter a lower rate.
What the results mean
Profit per unit is the sale price minus everything else: landed cost, inbound shipping, other costs, the referral fee, the FBA fee, storage, and ads, refunds and promos as a share of the price.Net margin is that profit divided by the price. ROI is profit divided by landed cost plus inbound shipping: what each dollar you put into inventory earns back.
Break-even ACoS is your profit before advertising, divided by the price. Any campaign running above it loses money on each ad sale. Max CPC turns that into a bid: if 12% of clicks become orders, each click is worth 12% of what you can afford to spend per sale. Manage campaigns against break-even ACoS, and judge the business by TACoS.
The grey box compares this with what a fees-only calculator would show you. The gap is usually large. On the example, fees-only says about 40%. After ads, refunds and promos it's under 17%.
What's a good margin?
There's no single right answer, but for scale: our own private-label store ran at about 21% net margin over the last 12 months, after cost of goods, fees, ads, refunds and promos. Amazon's fees took about 30 cents of every sales dollar, ads about 13-14 cents, and refunds about 7. If a product only works on a fees-only calculator, it doesn't work. Our product validation guidecovers the checks we run before ordering inventory, and is Amazon FBA worth it puts these numbers in context.
Want a monthly P&L too?
This page answers whether a product should make money. To track whether it did, month by month, use our free profit spreadsheet. It has the same per-unit math plus a 12-month P&L tab, and works in Excel and Google Sheets.
When to move to a profit tool
A calculator is for deciding whether to launch something. Once you have more than a handful of SKUs, or want profit daily instead of after the month closes, a profit tool that reads your settlement data does this for every product, every day.
Sellerise is what we use.Try Sellerise: monthly plans are 10% off for your first year through our link.
sellerboard is the alternative we recommend if you want a simpler dashboard.Try sellerboard: a two-month free trial through our link.
Common questions
Is this calculator free? Yes. No signup, no email, and nothing to download. Your inputs are saved in your own browser so they're still there when you come back, and they're never sent to us.
Does it work for marketplaces other than the US? The math works anywhere. Enter your own marketplace's referral rate and FBA fee, in your own currency, and ignore the dollar sign.
Why doesn't it work out the FBA fee for me? Amazon's fee depends on size tier, shipping weight and price, and changed three times in 2026. Amazon's Revenue Calculator and your Fee Preview report are the sources of truth, so we take the fee from there instead of guessing.
Is it the same as the spreadsheet? Same per-unit math and the same example. The spreadsheet adds a monthly P&L and handles several SKUs side by side.