Break-even CPA: the calculation everyone gets wrong (with a COD and card example)
Alex Nogueira · 2026-10-07
Result
Break-even CPA: the calculation everyone gets wrong
Formula
Break-even CPA (Cost per Acquisition) is essential for understanding when your campaigns are profitable. The basic formula is:
Break-even CPA = (Product Cost + Shipping Cost + Taxes + Returns) / (1 - Profit Margin)
For a product that costs R$ 100, with R$ 10 shipping, 10% taxes (R$ 11), and a desired profit margin of 30%, the calculation would look like this:
Break-even CPA = (100 + 10 + 11 + 10) / (1 - 0,30) = R$ 212,86
According to this formula, for each sale, you can spend up to R$ 212,86 on ads without taking a loss.
Returns
Returns directly impact your break-even CPA. If you expect a 10% return rate, that needs to be factored into the formula. For example, if you sell 100 units and 10 are returned, your cost per acquisition needs to include the loss from those sales.
If we use the same product, with a 10% return rate, we need to add the cost of returns to the calculation and recalculate the CPA. You can do that like this:
New Break-even CPA = (Product Cost + Shipping Cost + Taxes + (Returns x Product Cost)) / (1 - Profit Margin)
Taxes
Taxes are another factor you can't ignore. Depending on your tax setup, taxes can vary quite a bit. On average, calculate 10% to 20% of the product value. For a R$ 100 product, use R$ 15 in taxes and include it in your break-even CPA.
Measured LTV
LTV (Lifetime Value) is crucial for understanding customer returns. If a customer's average LTV is R$ 500 and you expect them to make three purchases over time, that impacts the CPA you can spend.
When calculating LTV, consider retention rate and purchase frequency. A higher LTV lets you run a higher CPA, giving your campaigns more flexibility.
Safety margin
Finally, a safety margin protects you against unexpected fluctuations. We recommend adding a safety margin of 10% to 20% to your break-even CPA. If your break-even CPA is R$ 212,86, add 20% for a safety margin.
That means your ideal CPA for campaigns would be around R$ 255,43. This helps make sure that even during bad months, you can still stay profitable.
What's your average break-even CPA considering these factors? Share your numbers!