Start with unit economics
Your ad budget should be constrained by the economics of an order, not by a fixed percentage copied from another store. First understand how much contribution is available before advertising.
What is ad cost per order?
Ad cost per order, or CPA, is the advertising spend required to generate an order. Compare this number with the contribution available from that order to understand whether acquisition is sustainable.
Calculate break-even acquisition cost
A simple approach is to calculate how much contribution is available before advertising. Your break-even ad cost is the amount you can spend per order before the order reaches zero profit, after the other relevant costs are included.
Set a target instead of only chasing break-even
Break-even is a limit, not necessarily a good target. If you want a specific profit per order, your allowable advertising cost should be lower than the break-even amount by that target profit.
Watch the whole funnel
CTR and conversion rate matter, but so do RTO, refunds, payment fees, shipping and product costs. A low CPA can still produce poor profit if downstream costs are high.
Why RTO changes your ad economics
For COD businesses, returned orders can create additional costs and reduce expected revenue. Include expected RTO effects when evaluating the real cost of acquiring an order.
A simple decision rule
If your actual ad cost per order is below your sustainable limit, acquisition may be economically viable. If it is above that limit, increasing ad spend can increase sales while reducing profit.
Use the SellProfit Ad Cost Calculator
Enter your order economics in the Ad Cost Calculator to estimate the advertising cost per order you can support.
Frequently asked questions
How much should I spend on e-commerce ads?
There is no universal percentage. Your sustainable ad budget depends on your product margin, fulfillment costs, fees, RTO or refunds, and the profit you want to keep.
What is break-even CPA?
Break-even CPA is the maximum advertising cost per acquired order that leaves the order at approximately zero profit after the other included costs.
Can a low CPA still be unprofitable?
Yes. A low CPA does not guarantee profit if product, shipping, payment, platform, RTO or refund costs consume the available contribution.