Your break-even CPA is your average order value plus shipping charged, minus product cost, postage, packaging and payment fees. It is usually much lower than a gross-margin estimate suggests, because shipping and fees eat a large share of each order.
Ask a founder what CPA they can afford and you'll usually hear a number based on gross margin. "Our margin is 80%, so on a $60 order we can spend $48." It sounds right, and it's one of the most expensive mistakes in ecommerce.
What gross margin leaves out
Gross margin only counts the product. Every order also carries postage, packaging, pick and pack, payment fees and a share of returns. On a $56 order with $8 of product cost, those extras can easily add up to $14, while the shipping you charge the customer only claws back part of it.
| Per order | |
|---|---|
| Average order value | $56.00 |
| Shipping charged | +$6.00 |
| Product cost | -$8.40 |
| Postage and packing | -$12.00 |
| Payment fees | -$1.80 |
| Break-even CPA | about $40 |
So the real ceiling is about $40, not $48. If Meta is delivering orders at $64, every new customer loses about $24 on the first purchase. Scale that, and you scale the loss.
Three ways to raise the ceiling
- Lift order value. Bundles and a free-shipping nudge move the whole equation. A $75 bundle can carry a $50 CPA where a $45 single can't carry $34.
- Cut variable cost. Renegotiate postage, right-size packaging, review payment providers.
- Earn the second order. Repeat purchase is what lets you pay more than the first order is worth. Without email flows, that's a hope, not a plan.
Know the number before you scale the spend.
Work out yours in two minutes with the break-even ROAS and CPA calculator.
Break-even ROAS and CPA calculator
Frequently asked questions
What is break-even CPA?
The most you can spend on advertising to win one order without losing money: your contribution per order before ads.
Why is my break-even CPA lower than my margin suggests?
Gross margin only counts product cost. Postage, packaging, payment fees and returns also come out of every order.
Written by Shimeez Bok, founder of Growth Alchemy, an ecommerce growth studio in Auckland, New Zealand.
