eCommerce Profit Margin Calculator
Your true per-unit margin — COGS, shipping, ads, platform fees — plus monthly break-even units and profit.
Business tools · Free
About the eCommerce Profit Margin Calculator
Revenue is vanity, profit is sanity. The single most common way small eCommerce sellers go broke is scaling a product they think makes $12 a unit — when shipping, platform fees, and ad spend actually leave them $2. This calculator reveals your true per-unit margin and the monthly unit count that covers your fixed costs.
Enter your sale price, product cost, shipping, ad spend per unit, and the percentage your platform skims. The result is the number that matters: what you actually keep per sale. Then add your monthly fixed costs to see how many units it takes just to break even.
Platform fees are bigger than they look. A 10% marketplace fee plus 3% payment processing is really 13% of revenue gone before you've paid for anything. On a $35 item that's $4.55 — often the difference between a healthy and a dead product.
Ad spend is a variable cost, not a marketing nicety. If a sale costs $8 in ads, that $8 belongs in your unit economics, not in a separate "marketing" spreadsheet. CAC that exceeds your gross margin is a treadmill, not a business.
Break-even units is your real target. Knowing you need 40 sales a month before profit begins (the default example) tells you whether the product is a business or a hobby. Many sellers quit not from lack of revenue, but because they never did this one calculation.
How to use it
- Enter the sale price. What the customer pays, per unit.
- Enter product cost and shipping. Your landed cost and fulfilment per order.
- Add ad spend per unit. Customer acquisition cost per sale.
- Set the platform fee percentage. Marketplace commission plus payment processing.
- Add monthly fixed costs. Software, storage, subscriptions — anything that doesn't scale with units.
- Read break-even units and monthly profit. The unit count that covers fixed costs, and profit at your real volume.
Frequently asked questions
How does the profit margin calculator calculate margin per unit?
Margin per unit is the sale price minus product cost, shipping, ad spend per unit and the platform fee (fee % × sale price). With the defaults ($35 price, $10 product cost, $5 shipping, $4 ad spend, 10% fee) the fee is $3.50, the true unit cost is $22.50 and you keep $12.50, a 35.7% margin.
How are break-even units calculated in the profit margin calculator?
Break-even units are monthly fixed costs divided by margin per unit, rounded up to a whole unit. With $500 of fixed costs and a $12.50 margin you need 40 sales a month; at the default 200 units, monthly profit is $2,000. If your unit margin is zero or negative, no volume breaks even and the tool tells you to reprice or cut costs.
What profit margin does the profit margin calculator consider healthy?
The tool labels 30% or more as 'Healthy for most resale' and anything lower as thin. Note that this percentage is after product, shipping, ad and platform costs but before fixed costs and income tax, so it is not your net profit margin. What counts as healthy varies by category and price point.
Is the platform fee in the profit margin calculator charged on the sale price only?
Yes, the percentage is applied to the sale price only. Some marketplaces also charge on the shipping the buyer pays, or add a fixed per-order fee such as a payment processor's per-transaction charge. Fold those into the fee percentage or the shipping field so they aren't missed.
What costs does the profit margin calculator not include?
It does not model returns and refunds, chargebacks, discount codes, sales tax, income tax or your own time. If returns are common in your category, add an expected per-unit return cost to the product cost or shipping field to keep the margin realistic.
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