Max CPA Calculator

Three CPA lines, derived from your margin

Everything starts with what one order leaves behind after variable costs:

margin per order = AOV × contribution margin %

With the defaults that is €80 × 55% = €44. From that single number the calculator draws three lines:

break-even CPA = margin per order
12-month max CPA = margin × (1 + repeat orders)
recommended target = 12-month max × 0.8

Pay €44 for a customer and the first order pays you back exactly. Add the 0.8 repeat orders a typical customer places over the year and each acquisition carries 1.8 orders of margin, so the ceiling rises to €79. The recommended target sits 20% under that ceiling, because your repeat-rate estimate and your tracking are both less precise than they feel.

The payback trade-off

Bidding between break-even and the 12-month max is a cash-flow decision, not a math error. At a €60 CPA on these numbers you lose €16 on the first order and earn it back as repeat orders arrive. That is fine if you have the cash to wait and the retention to collect. It is dangerous if either is shaky. Companies with strong balance sheets deliberately buy customers at a first-order loss because they know the money comes back. Companies without one should bid closer to break-even and grow slower on purpose.

Where the repeat number must come from

The repeat-orders input is the most abused field in this kind of math. It has to come from cohort data: take customers acquired 12 or more months ago and count the orders they actually placed after the first. Hope is not a source. If you assume 0.8 repeat orders and your cohorts deliver 0.3, every bid you placed against that ceiling was too high, and you find out two quarters later. No cohort data yet? Set it to zero, bid to first-order break-even, and earn the right to raise it as the evidence comes in.