How to use the calculator
Pick your size tier at the top, then enter your selling price and product cost, your inbound shipping and prep per unit, the referral fee percentage for your category, and the FBA fulfillment fee for your product. Use the sliders for storage, PPC per unit, and your return rate. The result updates instantly, and nothing you type is saved.
A worked example you can follow
Here is the calculator's default scenario: a $29.99 product costing $5.00, with $0.80 inbound shipping, $0.50 prep, a 15% referral fee, a $3.22 FBA fee, $0.50 storage, $3.00 of PPC per unit, and a 5% return rate.
Worked example · $29.99 unit
Where the $29.99 actually goes
Selling price$29.99
Product cost (COGS)−$5.00
Inbound shipping + prep−$1.30
Referral fee (15%)−$4.50
FBA fulfillment fee−$3.22
Storage per unit−$0.50
PPC ad spend per unit−$3.00
Return loss (5%)−$0.29
Net profit per unit$12.18
That is a 40.6% net margin. Amazon's own fees (referral plus FBA plus storage) take about $8.22 of the $29.99 here, which is why checking them together matters so much.
What counts as a healthy margin on Amazon
Margins vary by category, but a useful rule of thumb is to keep your product cost around 20% to 30% of the selling price, since Amazon's fees plus PPC will typically consume another 40% to 50% before you keep anything. A net margin above 20% after PPC is generally considered healthy for FBA. Under about 10% leaves almost no room for a bad PPC month or a fee increase.
The lever that most often decides the outcome is PPC. Because ad spend comes out of what is left after Amazon's fees, a product with a thin gross margin cannot absorb much advertising. Use the tool to see how far you can push PPC before the unit turns unprofitable, then set your bids accordingly.
Using this to make better decisions
Run a product through the calculator before you commit to inventory, and you will know its floor before Amazon does. If the margin is thin, the usual levers are lowering COGS through better sourcing, reducing your FBA fee with smaller or lighter packaging, or trimming PPC. This is general educational guidance, not financial advice, so always verify your current fees in Seller Central.
Glossary of terms
New to selling online? Every term this calculator uses is defined below in plain language, with a quick example where it helps. No prior experience assumed.
- COGS (Cost of Goods Sold)
- What it costs you to obtain or make one unit of the product itself, not counting shipping or ads.Example: buying an item from a supplier for $8 means a COGS of $8.
- Referral fee
- The percentage Amazon keeps from each sale, set by product category and charged on the selling price.Example: a 15% referral fee on a $29.99 sale is about $4.50.
- FBA fulfillment fee
- A flat per-unit fee Amazon charges to pick, pack, and ship your order through Fulfillment by Amazon. It depends on size and weight.
- Size tier
- Amazon's classification of your product by dimensions and weight. It sets your FBA fee, which is why the calculator asks for it first.
- Storage fee
- A monthly charge for keeping your inventory in Amazon's warehouses, spread here to a per-unit cost.
- Inbound shipping
- What it costs to get your inventory from your supplier into Amazon's warehouse, per unit.
- PPC (pay per click)
- Amazon's advertising, where you pay each time a shopper clicks your ad. Shown here as an average cost per unit sold.
- Return rate
- The share of your orders that customers send back, written as a percentage.Example: a 5% return rate means about 5 of every 100 orders come back.
- Net profit per unit
- What you actually keep from one sale after every cost has been subtracted from the price. This is the number that tells you whether a product makes money.
- Net margin
- Net profit shown as a percentage of the selling price, so products at different prices can be compared on equal footing.Example: $12 profit on a $30 sale is a 40% net margin.
- Gross vs. net
- Gross describes a figure before costs are removed; net is what remains after. Net is the honest number for decisions.
Frequently asked questions
What referral fee percentage should I use?
Referral fees are set by product category and are typically around 8% to 15%. Check the current rate for your exact category in Amazon Seller Central and enter it in the calculator.
How do I find my FBA fulfillment fee?
Amazon sets the FBA fee by your product's size tier and weight. Select your size tier at the top of the calculator, then enter the specific fee shown for your product in Seller Central.
Does the calculator store the numbers I enter?
No. Every calculation happens locally in your browser. Your costs and margins are never collected, stored, or transmitted.
Is this financial advice?
No. The results are estimates to help with your own planning, not financial, tax, or accounting advice. Always verify your current Amazon fees before making decisions.