Contribution margin: what each order really adds to your business
Gross margin tells you how much is left after the cost of the product. Contribution margin goes one step further: it also takes out every cost that only happens because an order happened, such as marketplace fees, payment processing, packaging, and shipping you pay for. What is left is the amount each sale contributes toward your fixed costs (software, subscriptions, tools) and, after those are covered, your profit.
The formula
Contribution margin = sale price − all variable costs per order
Contribution margin ratio = contribution margin ÷ sale price
Variable costs are the ones that go up with every order and disappear when nothing sells. For most online sellers that list includes:
- Product cost (materials, or what you paid the supplier, including landed cost)
- Marketplace transaction and referral fees
- Payment processing fees
- Packaging and inserts
- Shipping labels you pay for, minus any shipping the buyer paid
- Per-order ad costs (for example, a fee charged only when an ad drives a sale)
- An allowance for returns and refunds
Fixed costs, such as a monthly store plan, design software, or a subscription you pay whether or not you sell, are not included. They get covered by the total contribution of all your orders.
Worked example (example numbers)
Say you sell a printed tote bag for $30 and charge $5 shipping. The numbers below are illustrative, so plug in your own fees and costs.
| Line | Amount |
|---|---|
| Revenue (item + shipping charged) | $35.00 |
| Product cost (blank bag + printing) | −$9.00 |
| Marketplace + payment fees (example 10% + $0.45) | −$3.95 |
| Packaging | −$0.80 |
| Shipping label | −$5.60 |
| Returns allowance (example 2% of revenue) | −$0.70 |
| Contribution margin | $14.95 |
The contribution margin ratio is $14.95 ÷ $35.00, about 42.7%. Compare that with gross margin on the item alone, ($30 − $9) ÷ $30 = 70%. The gap between 70% and 43% is exactly the stuff that quietly eats sellers who price from gross margin.
Three ways to use it
1. Break-even volume
Divide your monthly fixed costs by contribution margin per order to see how many orders you need just to cover them:
Break-even orders = monthly fixed costs ÷ contribution margin per order
With $90 a month in fixed costs and $14.95 per order, you need about 6 orders a month before you make a dollar of profit. More on this in our break-even guide.
2. Maximum ad cost per sale
Contribution margin before ads is the most you could ever spend to win one sale and still break even on it. If an ad platform costs you $6 per sale on average, the tote above still contributes $8.95. If it costs $16 per sale, every ad-driven order loses money.
3. Comparing products and channels
Two products with the same price can have very different contribution margins once shipping weight and fees are counted. Ranking products by contribution margin per order (and per hour of your time, if you make them) shows which ones deserve more listings, photos, and promotion.
Common mistakes
- Leaving out shipping you pay for because the buyer "paid shipping". Only the difference matters.
- Forgetting that some marketplace fees apply to shipping and tax, not just the item price.
- Counting fixed costs per unit, which makes small-volume months look worse than they are and hides which products actually perform.
- Ignoring returns. Even a small refund rate shaves the margin on every order.
Related reading: gross vs net profit margin and markup vs margin. Educational content only, not financial or tax advice.
More seller guides
- Etsy fees explained: what Etsy actually takes from each sale
- How to calculate your Shopify profit margin (and what a good one looks like)
- Amazon FBA fees in 2026: what you pay and how to estimate it
- Quarterly estimated taxes for online sellers: a plain-English guide
- How to calculate COGS (cost of goods sold) for your online store
- Reorder point formula for small online shops (with safety stock examples)
- How to track returns and refunds as an online seller (and calculate refund rate)
- How to make a simple monthly profit and loss statement for your online shop
- What to include on an invoice: a checklist for small sellers and makers
- How to price handmade products: a simple formula that covers fees and pays you
- Break-even point for online sellers: formula, example, and how to lower it
- Inventory turnover ratio: how fast your stock actually sells
- Gross vs net profit margin: what each one tells an online seller
- Landed cost: the true cost of a product once it reaches your shelf
- Markup vs margin: why a 50% markup is not a 50% margin
- Free shipping vs charging for shipping: which one makes you more money?
SellerSheetKit is not affiliated with Etsy, Shopify, or Amazon. Fee figures are summarized from official sources on the date above and can change; verify against your seller account. Educational content only — not tax, legal, or accounting advice.