Break-even ROAS: Why Most Target ROAS Values Are Set Wrong

"We run on a ROAS of 4." We hear this regularly in first calls. Asked where the 4 comes from, the answer is almost always one of three: a blog post, the previous agency, or "it just settled there".

None of those is a calculation. And that gets expensive, because target ROAS decides how much budget an account is allowed to spend. Set it too high and you throttle profitable growth. Set it too low and you buy revenue that costs you money.

What break-even ROAS actually is

Break-even ROAS is the point where advertising exactly carries itself — no more, no less. It depends on exactly one figure: how much money is left per order before advertising is paid for.

That figure is the contribution margin, and it is not the same as gross margin:

Contribution margin = (avg. order value × gross margin) − fixed cost per order

Fixed cost per order is the part almost everyone forgets: shipping, payment provider fees, packaging, return rate. At a €120 basket and 45% gross margin you have €54. Subtract €8 in fixed costs and you have €46 — 15% less room than the gross margin suggests.

From this follows directly:

Break-even CPA  = contribution margin
Break-even ROAS = avg. order value ÷ break-even CPA

In the example: break-even CPA €46, break-even ROAS 2.61. Everything above is profit, everything below is loss. The frequently quoted "ROAS 4" would be far too conservative here — and would leave scalable volume on the table.

The reasoning error in target ROAS

Break-even is the floor, not the goal. Running at 2.61 means working at zero margin. So you need a buffer — and this is exactly where the most common arithmetic mistake happens.

It is wrong to subtract the profit share from the contribution margin. It is correct to subtract it from the order value, because "10% margin" normally means 10% of revenue:

Max. CPA for target margin = contribution margin − (avg. order value × target margin)
Min. ROAS                  = avg. order value ÷ max. CPA

In the example with a 10% target margin: €46 − €12 = €34 maximum CPA, so a minimum ROAS of 3.53.

The difference is not academic. The wrong variant yields a €41.40 CPA and a target ROAS of 2.90 — you would believe you were profitable while roughly €7 per order is missing. At 300 orders a month that is over €2,000 monthly that nobody sees in the report, because ROAS is "on target".

We tripped over exactly this error in our own ROAS calculator and fixed it. The tool now uses the second variant and greys out a target margin that simply isn't reachable with the values entered.

When the calculation isn't enough

Three situations where break-even ROAS alone misleads:

Repeat purchase rates. If a customer buys three times on average, you may spend more on the first order than it carries by itself. Then you steer on customer lifetime value, not ROAS — a different calculation with different data requirements.

Lead gen instead of e-commerce. There is no order value here. The substitute: average deal value × lead-to-customer conversion. Anyone who doesn't know that conversion rate doesn't know their target CPA — and should measure it before guessing bid targets.

Volatile basket sizes. An average across very different products produces a target ROAS that is right for none of them. Then the calculation belongs at product-group level, not account level.

Common questions

Is a higher ROAS always better?

No. A very high ROAS almost always means you are spending too little. If your break-even is 2.6 and you run at 8, you are leaving profitable volume behind — every additional order between 8 and 3.5 would still have been earned.

Why does the ROAS in Google Ads differ from my own calculation?

Usually attribution and tax. Google counts conversions on its own model and by default uses the revenue value you pass in — whether that is gross or net depends on your tracking setup. Check which value you are actually sending before comparing numbers.

How often should I recalculate break-even?

Whenever purchase prices, shipping costs or payment fees change — at minimum once per quarter. The most common case in practice: costs have risen and the target ROAS has sat unchanged in the account for two years.

Does this apply to Meta and TikTok too?

The calculation is platform-independent, because it comes from your own unit economics, not from the ad account. What differs is attribution — and therefore which channel an order gets credited to. Break-even stays the same.

What you can do today

1. Get three numbers: average order value, gross margin after COGS, fixed cost per order.
2. Work out the contribution margin — or use the ROAS calculator, which runs locally in your browser.
3. Compare the resulting minimum ROAS with the target currently set in your account.
4. If the two are more than 20% apart, you have either given away growth or bought losses.

If you get stuck at step 1 because fixed cost per order isn't recorded anywhere cleanly, that is the actual finding — and a good reason for an intro call. How we work accounts through this is described under Google Ads.