How to Calculate Whether a Product Is Worth Selling
The unit-economics math for one product: cost of goods, platform and payment fees, shipping, returns, ad cost per order, contribution margin and break-even — with a worked example.
A product is worth selling when each order reliably leaves money after every per-order cost. Add up cost of goods, platform and payment fees, shipping, a returns allowance and your expected ad cost per order, subtract that from the price, and you get contribution margin per order. If it's comfortably positive and clears your break-even, the product can work. This guide is the calculation for one specific product — not which product types tend to be high-margin.
"Is this product worth selling?" is ultimately a math question, and the math is not the sticker price minus the wholesale cost. It's the price minus every cost that occurs each time you sell one. This guide walks that calculation for a single product.
This is the per-product math. It's different from knowing which kinds of products tend to carry fat margins — that's high-margin products to sell online. Here we compute the actual contribution margin and break-even for one specific item.
Why price minus cost isn't the answer
A product that costs $10 and sells for $30 looks like a 67% margin. But payment and platform fees, shipping, the occasional return and the ad spend it takes to get the order all come out of that gap. Once they do, a "healthy" margin can turn out to break even — or lose money on every sale. The number that matters is contribution margin per order: what's left after all per-order costs.
The per-order costs to count
Line up every cost that recurs with each sale. Miss one and your margin is fiction.
- Cost of goods (COGS): What you pay for the unit itself, landed — including inbound shipping and any duties.
- Platform & payment fees: Processor fees (often a percentage plus a flat fee) and any per-transaction platform cut.
- Outbound shipping: What it costs to get the product to the buyer, minus whatever shipping they pay you.
- Returns & refunds allowance: Expected return rate applied across all orders — returns cost you even when only some orders come back.
- Ad cost per order: Your expected ad spend divided by the orders it produces. This is usually the biggest and most variable line.
Contribution margin, step by step
Contribution margin per order is simply price minus the sum of all the per-order costs above. Positive means each sale contributes toward your fixed costs and profit; negative means you lose money by selling more.
- 1Start from the selling priceUse the price a buyer actually pays, net of any discount or coupon you routinely offer.
- 2Subtract COGS and feesTake out the landed unit cost, then platform and payment fees.
- 3Subtract shipping and a returns allowanceDeduct your net outbound shipping and the expected cost of returns spread across all orders.
- 4Subtract ad cost per orderTake out your realistic acquisition cost. What remains is contribution margin per order.
A worked example
The numbers below are illustrative and hypothetical — invented to show how the lines combine, not real market data. Plug in your own figures; the structure is what matters.
| Line | Amount | Note |
|---|---|---|
| Selling price | $40.00 | What the buyer pays |
| Cost of goods (landed) | −$12.00 | Unit + inbound shipping |
| Platform & payment fees | −$1.80 | ~3% + $0.30, example rate |
| Outbound shipping (net) | −$4.00 | After buyer-paid shipping |
| Returns allowance | −$2.00 | ~5% return rate, spread across orders |
| Ad cost per order | −$12.00 | Example acquisition cost |
| Contribution margin | = $8.20 | Per-order profit before fixed costs |
In this hypothetical, $40 leaves $8.20 per order after per-order costs — roughly a 20% contribution margin. Whether that's good depends on your fixed costs and volume, but notice how the ad line alone nearly decides the outcome: at a $20 ad cost per order instead of $12, this product would lose money on every sale.
Break-even: turning per-order margin into a decision
Contribution margin tells you the profit per order; break-even tells you how many orders you need before the product pays for its fixed costs. Divide your monthly fixed costs (subscriptions, tools, a share of overhead) by the contribution margin per order:
Cross-check that required volume against your demand research — see how to research product demand. A product whose break-even needs more orders than the demand can plausibly supply isn't worth selling, however good the per-order margin looks.
What to calculate first
Work the math in the order that kills bad ideas fastest:
- 1Rough contribution margin firstA quick price-minus-all-costs pass weeds out products that can't work before you invest more effort.
- 2Stress the ad cost lineBecause acquisition cost dominates and varies most, test the product against a pessimistic figure early.
- 3Compute break-even volumeTurn the margin into the order count you'd need, then sanity-check it against realistic demand.
- 4Decide, then validate
Frequently asked questions
What's the difference between gross margin and contribution margin?
Gross margin is price minus cost of goods only. Contribution margin subtracts every per-order cost — fees, shipping, a returns allowance and ad cost per order — so it reflects what a sale actually leaves you. Contribution margin is the number that decides whether a product is worth selling.
Why does ad cost per order matter so much?
For most new stores, acquisition cost is the largest and most variable per-order expense. A product that's profitable before ad spend can lose money after it. Always include a realistic figure, and re-run the math with a pessimistic one to see whether the product still clears zero.
How many sales do I need to break even?
Divide your monthly fixed costs by the contribution margin per order. That's your break-even order count. Then check it against realistic demand — if you'd need more orders than the market plausibly supplies, the product isn't worth selling regardless of its per-order margin.