Break-even CPA and ROAS: the number to compute before you test
Margin tells you whether a product works in principle. Break-even CPA tells you whether you can afford to advertise it — and that is the decision you are actually making when you look at a supplier listing. Here it is, worked from a real cost model.
Break-even CPA and ROAS calculator
Every amount in the same currency as your sell price. The defaults are this page’s worked example: a product landing at €5.80, including €1.01 of import VAT that a VAT-registered seller reclaims.
19.95 − 3.46 VAT − 0.83 fees − 4.79 landed after reclaim = 10.87 per sale before advertising. Break-even ROAS = 19.95 ÷ 10.87 = 1.84 (1.52 if your ad platform receives revenue without VAT).
Assumes one unit per order. It stops at contribution per sale: returns, refunds, chargebacks and your own time are not in it. Nothing you type leaves this page.
Break-even CPA is what remains of the sale after everything that is not advertising. Sell price, minus output VAT, minus payment fees, minus landed cost. Spend less than that per customer and the unit makes money. Spend more and you are buying revenue at a loss, however good the margin percentage looks.
The same product at five prices
One product landing at €5.80 a unit — €4.20 goods, freight split across 50, duty and import VAT in the EU. Only the sell price changes:
| Sell price | Markup | Margin | Break-even CPA | Break-even ROAS |
|---|---|---|---|---|
| €14.95 | ×2.6 | 46% | €6.88 | 2.17 |
| €19.95 | ×3.4 | 54% | €10.87 | 1.84 |
| €24.95 | ×4.3 | 60% | €14.85 | 1.68 |
| €29.95 | ×5.2 | 63% | €18.84 | 1.59 |
| €39.95 | ×6.9 | 67% | €26.81 | 1.49 |
Look at what the two columns on the right do. Margin climbs from 46% to 67% — a respectable but bounded improvement, and one that gets less impressive the further you go. Break-even CPA goes from €6.88 to €26.81, almost four times.
That gap is the whole argument for planning in amounts rather than percentages. Margin is a ratio and it flatters; CPA headroom is money and it is what you actually hand to Meta. Two products can share a 60% margin and be completely different businesses to run, because one leaves you €4 a customer and the other leaves you €40.
Break-even ROAS is the same number, inverted
Ad platforms report return on ad spend, not CPA. Break-even ROAS is revenue per order divided by break-even CPA: at €19.95 with €10.87 of headroom it is 19.95 ÷ 10.87 = 1.84. A campaign reporting a ROAS above 1.84 on this product makes money on each sale before overheads; below it, the ads cost more than the sale leaves over. The last column of the table is that division for each price. Divide by the revenue figure your platform actually receives: if your store sends it without VAT, the €19.95 row breaks even at 1.52 instead.
What the 3× rule actually buys you
Every guide teaches a 3–5× markup on landed cost. It is a decent heuristic and it hides the number it is a heuristic for. Same product, same €5.80 landed:
| Markup | Sell price | Break-even CPA |
|---|---|---|
| 3× | €17.40 | €8.83 |
| 4× | €23.20 | €13.46 |
| 5× | €29.00 | €18.08 |
Whether €8.83 per customer is workable is not a question the multiple can answer. In a niche where acquisition runs €6, 3× is comfortable. Where it runs €12, 3× loses money on every sale while displaying a healthy-looking 3× markup and a 51% margin. The rule of thumb is not wrong; it is just answering a different question than the one you have.
The step most calculators skip
In the EU and UK the price a shopper sees includes VAT. That money was never yours. A calculator that takes the sell price, subtracts cost and calls the remainder profit has overstated it by roughly a fifth before it starts.
The full sequence, in order:
- Sell price — what the customer pays.
- Minus output VAT — 21% of the gross in the Netherlands, 20% in the UK.
- Minus payment fees — around 2.9% plus a fixed amount, charged on the gross.
- Minus landed cost — goods, freight per unit, duty, and import VAT that you cannot reclaim.
- What remains is break-even CPA.
Landed cost has its own ordering trap: duty is charged on goods plus freight, and import VAT on the duty-inclusive total. Getting that sequence wrong understates cost — the one direction an error must never go, because it tells you a bad product is fine. And below the customs threshold there is no duty at all, which changes the answer more than most people expect.
Rule change since this was written. Two of the thresholds below no longer hold as stated. From 1 July 2026 the EU charges a temporary €3 customs duty per item (per tariff classification) on low-value e-commerce parcels worth up to €150 imported from outside the EU, until 1 July 2028 (European Commission). In the US, duty-free de minimis treatment was suspended for shipments from all countries from 29 August 2025 (The White House, Executive Order). The figures on this page predate both changes.
What this number cannot tell you
- Your actual CPA. That comes from your ad account, not from arithmetic. Break-even CPA is the ceiling you are aiming under.
- Whether the product sells. A generous break-even on something nobody wants is still a generous break-even on nothing.
- Net profit. Returns, chargebacks, refunds and your own time are not in this figure. It stops at contribution per unit, deliberately.
- Repeat purchases. If customers buy twice, you can pay more than break-even to acquire them once — but that is a bet on retention you do not yet have evidence for.
MurmMargin computes this on the supplier listing you are looking at. Type your sell price and it prints the break-even CPA as the headline, with every assumption — VAT registration, payment fees, freight split, duty band — written beside it.
How MurmMargin works →→Questions
What is break-even CPA?
The most you can pay to acquire a customer before the sale stops making money.
What is break-even ROAS?
Revenue per order divided by break-even CPA: 19.95 ÷ 10.87 = 1.84 in the example above. Below that ROAS the ads cost more than the sale leaves over.
How do I calculate break-even CPA?
Sell price, minus output VAT, minus payment fees, minus landed cost. What remains is it.
Is a 3× markup enough?
On a €5.80 landed cost it leaves €8.83 per customer. Whether that is enough depends on your niche, which the multiple cannot tell you.
Why not just use margin percentage?
Because you spend money, not percentages. Two products at 60% margin can leave you €4 and €40 respectively.