The real cost of selling one unit online — shipping, processing fees, and returns all eat into a margin that looks fine until you count everything.
Maria runs a candle brand and sells her signature jar candle for $28. It costs her $9.50 in wax, fragrance oil, wicks, and the glass jar itself, so on a spreadsheet that looks like a 66% margin, more than enough to build a business on. When she pulls a full month of orders and actually adds up what leaves her bank account on every sale, the picture changes. Payment processing takes about $1.11 off that $28 order. The box, tissue paper, and shipping label cost her $1.80 in packaging. Shipping the candle to the customer, even at a discounted carrier rate, runs $7.40 because glass is heavy. Roughly one in twelve candles comes back broken or unwanted, and that cost has to be averaged into every order, not just the ones that get returned. Add it up and Maria's real margin per order is closer to 25%, not 66%. That is still a workable business, but it is a very different number to plan a budget, an ad spend limit, or a hiring decision around.
The gap between the sticker-price margin and the real one is not a rounding error. It is the difference between a business that looks healthy on a spreadsheet and one that is healthy in the bank account, and the two only line up once every cost that touches an order, not just the materials in it, gets counted before anyone calls a product profitable.
Every cost below quietly leaves the business between the moment a customer clicks buy and the moment that order is closed out for good. None of them show up if the only math being done is price minus cost of goods, and none of them are optional just because they are not itemized on the product page.
Costs that eat into the sticker-price margin on a typical online order
| What it is | Typical range | |
|---|---|---|
| Cost of goods (COGS) | Materials + manufacturing/sourcing cost per unit | Varies by product |
| Payment processing | Fee charged by your payment processor per transaction | About 2.9% + $0.30 per transaction is a common baseline |
| Shipping (outbound) | What you pay to ship the order, whether or not you charge the customer for it | Varies widely by weight, size, and carrier |
| Packaging | Box, mailer, inserts, tape | Often overlooked, but real and recurring |
| Returns / refunds | Lost product cost, return shipping, and restocking labor on returned orders | Apparel commonly sees 20 to 30% return rates, very different from most other categories |
| Ad spend per order |
Use your actual unit cost and a realistic target margin, including everything above and not just materials, to see what your price actually needs to be. Plug in Maria's numbers, $19.81 in landed cost per candle before returns and ad spend, against a 40% target margin, and the calculator will show a price meaningfully higher than $28, which is the gap between what she charges today and what she needs to charge to hit that margin sustainably.
Cost-Plus Price Calculator
Enter your full landed cost per unit (materials, packaging, average shipping, and payment processing), not just materials cost, to see the price that actually hits your target margin.
Suggested price
$42
Profit per unit
$17
Equivalent markup
66.7%
Not the same number as margin — see below
Returns cost more than the refund
A returned order doesn't just cost you the refund. You also lose the original outbound shipping, which is rarely recovered, often pay return shipping on top of it, and may not be able to resell the item at full price, or at all, if it comes back damaged or out of season. On a $50 order with a 20% return rate, that slice of orders effectively costs a quarter or more of revenue once outbound shipping, return shipping, and unsellable stock are added to the lost sale, not just the 20% headline number.
Return rate is not one number across all of e-commerce. It swings hard by category, and pricing or budgeting off a generic industry average instead of the number for your specific category is a common way founders get surprised by a quarter that looks nothing like their forecast.
Typical return rate by product category (blended averages, individual SKUs can run much higher or lower)
| Typical return rate range | Main driver | |
|---|---|---|
| Apparel and footwear | 20 to 30% | Sizing and fit |
| Home goods and furniture | 10 to 20% | Damage in transit or wrong fit for the space |
None of these red flags require a finance background to catch. They mostly come down to whether the full cost of an order, not just its materials, gets counted before decisions get made about pricing, discounts, and how hard to push paid acquisition.
Worth checking before scaling ad spend
0/4Once contribution margin per order has actually been calculated, the next question is where to focus first. The path below is a rough triage, not a replacement for doing the math on your specific product, but it is a reasonable place to start when the numbers are worse than expected and it isn't obvious why.
Where is most of your margin disappearing?
When you compare your product's sticker-price margin to its real contribution margin, where does most of the gap come from?
Return policy and sales tax rules vary by state
A handful of state-level rules can affect e-commerce unit economics beyond the operational costs already covered here. Some states set requirements around what a return or refund policy must disclose to the customer, which affects how freely a business can limit returns or charge restocking fees. Sales tax collection obligations also vary by state through economic nexus rules, meaning a business selling into enough states, or generating enough revenue in a state, can owe sales tax registration and collection duties that add real compliance cost, even when the tax itself is passed through to the customer. Neither of these figures into contribution margin the way shipping or COGS does, but both are worth checking before locking in a returns policy or expanding into new states.
What varies by state
Check your state's attorney general or consumer protection office for return policy rules, and your state's department of revenue for sales tax nexus and registration requirements.
Key Terms
Check your understanding
A product costs $12 in materials and sells for $30, an apparent 60% gross margin. After a $4.20 average outbound shipping cost, $1.17 in payment processing, $1.50 in packaging, and a 15% return rate on the product line, which number should actually drive whether this product's price gets raised?
An apparel brand offers free shipping on every order and hasn't built its cost into the product price. What is the most accurate way to describe what is happening to that shipping cost?
A founder calculates that a product earns a healthy $9 contribution margin per unit. On orders that came from a paid ad channel, customer acquisition cost averages $14 per order. What does this tell the founder about the paid channel specifically?
Ask a question about this lesson or share your take.
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| If the order came from a paid channel, its share of what you spent to acquire it |
| Highly variable, this is your CAC, allocated per order |
Run this against Maria's candle: $9.50 in cost of goods plus $1.11 in payment processing plus $1.80 in packaging plus $7.40 in outbound shipping already adds up to $19.81 against a $28 price, an 8% margin before a single return or ad dollar is counted. Layer in a return rate averaged across the product line and a realistic customer acquisition cost from paid ads, and a product that looked like a 66% margin winner on the spreadsheet can end up barely breaking even, or losing money outright, on the specific orders that came from paid channels. This is why contribution margin, not gross margin, is the number that should drive pricing, ad spend limits, and which products get pushed versus quietly discontinued.
| Electronics and accessories | 8 to 15% | Buyer's remorse or compatibility issues |
| Beauty and personal care | 5 to 10% | Lower because items are often not resellable once opened |
| Consumables (food, supplements) | 2 to 5% | Lowest because there is little to reconsider after a quick-use purchase |