Every ad metric needs a margin to mean anything
Revenue attributed to advertising is not money you keep. Out of it come the goods, the fulfilment, the marketplace commission and the payment fees. What remains is the only thing the ad spend can be paid from.
That is why a break-even ROAS exists at all, and why it is different for every product you sell. Once you know your contribution margin, the threshold falls out of it directly — no benchmark or industry average required. The ROAS calculator puts the two side by side, together with the ACoS that matches them.
Attributed is not incremental
Ad platforms report the sales they can attribute to themselves, which includes customers who would have bought anyway. The honest test is what happens to total sales when you turn the campaign off, not what the dashboard claims while it is running.
Treat reported ROAS as an upper bound. If a campaign only just clears break-even on attributed revenue, it is probably losing money on real revenue. The whole argument, and the test that settles it, is in ad attribution.
A healthy ratio can still run you out of cash
Lifetime value against acquisition cost is a ratio, and ratios have no clock in them. A customer worth €300 over three years, acquired for €60, gives a ratio of five to one — the kind of number that gets a budget approved. It says nothing about the thirty-six months you spend waiting.
The figure that governs how fast you can grow is the payback period: how long until a customer has returned, in contribution margin, what you paid to acquire them. Under three months, acquisition largely funds itself. Beyond twelve, every additional customer widens the hole before it fills it, and growth is limited by your bank balance rather than by demand. The LTV to CAC calculator reports both figures from the same inputs, the ratio and the months.
This is the mechanism behind businesses that fail while growing: the unit economics were genuinely sound and the cash arrived later than the bills. Both numbers are worth knowing, and when they disagree, the payback period is the one that decides what you can afford this quarter.
Spend is the last lever, not the first
Advertising multiplies whatever the rest of the business already does. If the margin is thin or the listing converts poorly, more traffic multiplies that too.
The order that tends to work is unglamorous. Fix the margin first: a product repriced from 22% to 30% contribution has lowered its own break-even ROAS by about a quarter, and every campaign behind it became viable without a single change to the ad account. Then fix conversion: sending the same paid traffic to a page that converts at 3% instead of 2% is a 50% improvement in return on identical spend. Only then raise the budget.
Done the other way round, the spend increase is what gets blamed when the numbers disappoint, and the actual constraint stays where it was.
Reading
The vocabulary of this section
Frequently asked questions
There is no universal figure, and benchmarks are close to useless here. A ROAS of 3 is comfortable on a 50% contribution margin and loss-making on 25%. The only meaningful reference point is your own break-even, which follows directly from your margin.
It is the point where the ad spend exactly consumes the contribution margin the sales produce: divide 1 by your contribution margin expressed as a decimal. A 25% margin gives a break-even ROAS of 4, a 50% margin gives 2.
They are inverses of each other: ACoS is ad spend divided by attributed revenue, ROAS is revenue divided by spend. An ACoS of 25% is a ROAS of 4. Neither says anything useful until you put it beside your margin.
Because the ratio has no clock in it. A customer worth five times what they cost to acquire, over three years, still leaves you funding the gap for three years. The payback period is what governs how fast you can afford to grow.