How the FBA profit calculator works
The calculator starts with monthly revenue (selling price × units sold) and subtracts every cost that comes out of an Amazon FBA sale. What is left is net profit for the month. All results update as you type, so you can test a price change or a lower landed cost in seconds.
| Metric | Formula | What it tells you |
|---|---|---|
| Net profit / month | Revenue − landed cost − referral fees − FBA fees − storage − PPC − other costs − plan fee − profit share | Cash you keep after everything you entered. A profit share, if entered, applies only when net profit is positive. |
| Profit per unit | Net profit ÷ units sold | Fully loaded profit on each sale |
| Net margin | Net profit ÷ revenue | How much of each sales dollar you keep |
| ROI on inventory | Net profit ÷ (landed cost × units) | Return on the cash tied up in stock each month |
| Break-even ACoS | Pre-ad profit per unit ÷ price | The highest ad cost of sale you can run before an ad-driven sale loses money |
| TACoS | PPC spend ÷ total revenue | Ad spend as a share of all sales, organic and paid |
What the margin colors mean
- Red (under 10%): one price war, fee change, or bad month of returns can wipe out profit.
- Amber (10–20%): workable, but there is little room for higher ad costs.
- Green (20% and up): enough cushion to absorb fee changes and keep advertising.
Pre-ad profit per unit is price minus landed cost, referral fee, FBA fee, and storage spread across units. It ignores PPC, other overhead, and the management fee, which is why break-even ACoS is a ceiling, not a target. If your break-even ACoS is 40% and your campaigns run at 35%, ad sales barely make money once overhead is counted.
Where to find the right fee inputs
The referral fee is 15% for most categories, but some categories use different rates or tiers, so check the referral fee table for your category in Seller Central. The FBA fulfillment fee depends on your product’s size tier and shipping weight. Measure the packaged unit and look up the matching fee, or use Amazon’s Revenue Calculator for an exact figure.
Limitations
The model assumes a steady month: one price, one fee level, and all units sold. Real months include refunds, coupons, price drops, and stockouts. Landed cost should include freight, duties, prep, and inspection, not just the factory price. Treat the result as a planning estimate and recheck it with real settlement reports after launch.
Want a second set of eyes on your product numbers before you place an order?
Book a Free Strategy Call →If you want a team to handle sourcing, listing, PPC, and inventory for you, see our Amazon FBA automation service or see how our custom quotes work. The optional management fee and profit share fields let you test any agency quote against your numbers before you sign.