Break-Even ROAS Calculator

Written out

Break-even ROAS is 1 ÷ contribution margin, where contribution margin is (revenue − variable costs) ÷ revenue and variable costs include goods, fulfilment, payment fees and returns.

It is the ROAS at which an additional order adds nothing. Above it the campaign contributes; below it, it consumes.

The reciprocal relationship is what makes it counterintuitive: a small drop in margin produces a large rise in the required ROAS.

Running the numbers

At a 55% contribution margin, break-even ROAS is 1 ÷ 0.55 = 1.82.

Drop the margin to 45% and it rises to 2.22. Drop it to 35% and it is 2.86. Drop it to 25% and it is 4.00.

So a ten-point fall in margin from 55% to 45% raises the required ROAS by 22%, and a further ten points raises it by another 29%. The relationship accelerates.

That is why a fee increase, a freight rise or a supplier price change that seems modest can make a previously profitable campaign unviable overnight, with no change in advertising performance at all.

What gets missed

It is break-even on the campaign rather than on the business. Fixed costs: salaries, software, rent, the platform, sit outside it entirely, so a business running exactly at break-even ROAS is losing money by its whole fixed base.

It also uses contribution margin at the average order value, and if advertising attracts a different basket mix than organic traffic, the applicable margin differs.

What to do next

Recalculate it whenever costs change rather than annually. It is the anchor for every bid and budget decision, and an anchor calculated on stale costs is worse than none.

Then work out the target ROAS that covers fixed costs as well, by dividing total contribution needed, fixed costs plus profit target, by the revenue expected. That is the number the account should actually be managed to.

Using it in the other direction

The formula also answers a pricing question. If the achievable ROAS in your category is 2.2, the required contribution margin is 1 ÷ 2.2 = 45%, and any product below that margin cannot be advertised profitably in that channel at all.

That turns a media-buying constraint into a product selection criterion, and it is the more useful direction for a business deciding what to sell rather than how to bid.

It also explains why margin improvement is a marketing lever. Reducing cost of goods by five points does not merely add profit. It lowers the ROAS the account has to achieve, which widens the set of keywords, audiences and placements that are viable. That effect is invisible in any advertising report and it is frequently larger than anything bid optimisation delivers.

It is worth calculating break-even at the average order value the advertising actually produces rather than the site average. Paid traffic frequently buys a different basket from organic, often a single advertised product rather than a fuller cart, and using the site-wide figure overstates the contribution available.

Where the gap is material, the correction can move the break-even threshold by a fifth, which is enough to turn a campaign that looked profitable into one that is not.

Recalculating it after every cost change is the discipline; an anchor calculated on stale costs quietly misprices every campaign built on it.