ACoS
Ad spend as a percentage of the revenue it drove: the direct inverse of ROAS.
ACoS, advertising cost of sale, is ad spend divided by the revenue from those ads, as a percentage. It is the direct inverse of ROAS: a 4x ROAS is a 25% ACoS, since spending one to earn four means ads cost a quarter of the revenue they drove.
ACoS measures the efficiency of the advertising itself, on the revenue it directly produced, which is why it pairs with TACoS (the whole-business view) rather than replacing it. Like ROAS, an ACoS number only means something against your break-even: the ACoS you can afford is set by your margin. Because ACoS and ROAS are the same relationship written two ways, you only need one of them; what matters is anchoring it to break-even, since a 40% ACoS is comfortable on a high-margin product and a slow loss on a thin one.
Work out the margin-based target with the break-even ROAS calculator.
Put the number to work: the break-even ROAS calculator turns your margins into the ROAS you need, and a free Due Diligence Audit checks whether the figures you see are the ones you are getting. Back to the glossary.