Amazon FBA profit calculator: what one unit really earns
Referral fee, fulfilment, storage, shipping in and your own cost — all of it comes off before you earn a cent. Change any number and watch the margin.
Referral percentages and FBA fees depend on category, size tier and dimensions, and they change. Defaults here are a starting point — replace them with the figures from your own Seller Central fee preview.
What comes off, in order
| Charge | Typical figure | Notes |
|---|---|---|
| Referral fee | 15% for most categories, 8% for some | On the total sales price, including item and any gift wrap |
| Fulfilment fee | Varies by size tier and weight | Set by Amazon per unit picked and packed |
| Monthly storage | Cents per unit, rising over time | Long-term storage and aged inventory surcharges add on top |
| Per-sale charge | $0.99 on the Individual plan | Disappears at 40 sales a month — that is the break-even for upgrading |
The three numbers sellers get wrong
- Landed cost, not supplier cost. Freight, duty and prep belong in the unit cost, or every margin you calculate is fiction.
- Ad spend per unit, not per campaign. Divide total ad spend by units sold; that is what each sale paid for attention.
- Months in storage. A unit that sits five months pays storage five times, and the surcharge jumps after that.
Per unit is one number; the month is the real one
A single unit tells you whether the listing works. The month tells you whether the business does — returns, reimbursements, storage surges and ad spend all land there. Margin Guard takes your orders export and adds it all up, naming the items that are quietly losing money. Free for files up to 200 orders, no account or login.
Amazon seller bookkeeping with the tax split out: income, expenses, input tax credits and a quarterly summary of what you owe or get back.
GST/HST, Expense & Mileage Tracker — US$19