Amazon FBA Profit Calculator
Amazon takes its cut in four separate places, and sellers routinely discover the fourth one after the stock is already in the network. This puts referral fee, fulfilment, inbound and advertising against the same unit, then prints the two numbers that decide whether the product is worth listing at all — break-even ACoS, and return on the cash each unit ties up.
INPUTS
Six
RUNS IN
Your browser
EMAIL REQUIRED
No
FORMULA
Printed below
A product that clears 25% before advertising is a business. One that clears 8% is a hobby with storage costs.
- The calculator
Every fee against the same unit
Six figures from a single ASIN. Take the fee numbers from the Seller Central fee preview rather than from memory — they change, and the size tier boundaries are unforgiving.
Net profit = price − referral fee − FBA fee − landed cost − inbound and storage − advertising. Break-even ACoS is contribution before advertising divided by price: at the defaults that is 38.4%, meaning a campaign spending more than 38 cents per dollar of sales on this unit is losing money on it. Return on cost divides net profit by landed cost plus inbound, because on Amazon the constraint is usually cash tied up in stock rather than margin percentage — two products on the same margin can have very different reorder economics. Not modelled here: returns, which are worse on apparel than almost anywhere, long-term storage surcharges on ageing stock, and the monthly professional selling plan, all of which make the real figure slightly lower.
- Reading it
Margin decides whether to list. Return on cost decides what to reorder.
Two products on identical margins can have completely different claims on your cash.
At the defaults, a $34.99 unit gives up $10.94 to Amazon before a single cost of your own is counted — nearly a third of the price. Add $10.60 of landed cost and inbound, and $13.45 is left to cover advertising and profit. Spend the default $4.20 a unit on ads and you keep $9.25, a 26% net margin. That is a healthy product, and the number that made it healthy is the price point rather than the cost price.
Return on cost is the tile experienced sellers read first. At 87% it means every dollar of stock comes back with 87 cents of profit within one turn, which is what tells you whether to put the next reorder into this product or a different one. A product on the same 26% margin but a $22 landed cost returns far less per dollar committed, and in a business where cash is the constraint rather than shelf space, that difference decides the range.
- Pull fee figures from the Seller Central fee preview, never from memory
- Divide ad spend by total units sold, not by advertised units
- Re-run it after any size tier or fee change — both move more often than prices do
- Getting it wrong
Four ways FBA profit gets overstated
Every one of these makes a product look listable when it is not.
Guessing the size tier
A quarter of an inch or a few ounces moves a unit into the next tier and adds a dollar or more to every single sale. Weigh and measure the packed unit, then read the fee from the preview rather than estimating it.
Dividing ad spend by advertised units
Advertising is paid out of the whole product, not just the units a campaign was credited with. Dividing by attributed units flatters the per-unit figure badly on products where organic sales are strong.
Leaving out inbound, prep and storage
Freight into the network, labelling, polybagging and monthly storage are real per-unit costs that never appear on the fee preview. Slow movers carry storage for months and the surcharge on ageing stock is brutal.
Ignoring returns entirely
A returned FBA unit costs the outbound fulfilment fee and often the return processing, and it may come back unsellable. On apparel and electronics that alone can remove several points of margin from the figure above.
Our break-even ACoS calculator works the advertising side in more depth, and the Amazon TACoS calculator shows whether the account as a whole is becoming less dependent on ads.
- Questions
FBA profit FAQs
The questions this calculator usually raises.
What is a good profit margin on Amazon FBA?
Most established sellers aim for 15–25% net after advertising, and this calculator turns the tile green at 20%. Below 10% there is almost no room to absorb a fee increase, a competitor price cut or a bad return month, which is why the tile goes amber there. The figure that matters alongside it is return on cost: a 15% margin on cheap stock that turns six times a year is often a better business than a 30% margin on stock that turns twice.
What fees does Amazon charge FBA sellers?
Four that matter per unit: the referral fee, a percentage of the sale price that is 15% in most categories; the FBA fulfilment fee, a flat amount per unit set by size tier and shipping weight; monthly storage, charged by cubic foot and far higher in the last quarter; and long-term storage surcharges on stock that ages. On top of those sit the $39.99 monthly professional plan and, if you use them, prep and labelling services.
How do I calculate break-even ACoS on Amazon?
Contribution before advertising divided by the selling price. At the defaults here that is $13.45 on a $34.99 unit, or 38.4% — the point at which advertising exactly consumes the profit. A target ACoS is break-even minus whatever margin you actually want to keep, which is why a 38% break-even usually implies a target somewhere in the low twenties rather than anywhere near the break-even line.
Should I include the monthly seller plan in per-unit costs?
Not in this calculator, because it is a fixed cost rather than a per-unit one and allocating it distorts comparisons between products. If you want the all-in figure, divide the $39.99 by your monthly units and add it to the inbound and storage field — on any meaningful volume it is a few cents.
Does this work for FBM or Seller Fulfilled Prime?
Yes, with one substitution. Replace the FBA fulfilment fee with your own pick, pack and delivery cost per order and leave everything else alone; the referral fee is charged either way. FBM usually wins on bulky low-value items where the FBA fee is punitive, and loses on anything small and light.
How is this different from your profit margin calculator?
Fee model. The eCommerce profit margin calculator is platform-agnostic and models returns properly, which makes it the right tool for your own store. This one is shaped around Amazon specifically — referral percentage, a flat fulfilment fee by size tier, inbound and storage — and prints break-even ACoS, which only means anything on a marketplace.
- Next
Related tools and reading
CALCULATOR
The advertising ceiling in more depth, and what a target ACoS should be once you want to keep something.
GUIDE
Listing, advertising and inventory on Amazon and the marketplaces beyond it, in the order they actually matter.
FREE AUDIT
Five working days across six disciplines, including a per-ASIN read of which products are earning their storage.
Half the catalogue barely breaking even?
That is normal, and the fix is rarely the fee structure. The free audit reads profitability per ASIN and says which products deserve the next reorder and which should be wound down.