Return on ad spend, or ROAS, is the revenue you earn for every dollar of ad spend: the headline efficiency measure for campaigns where you can track the value of a sale.
Return on ad spend, or ROAS, is the revenue you earn for every dollar you put into ads. Spend a thousand dollars and generate four thousand in sales, and your ROAS is four to one, sometimes written as 400 per cent. It is the headline efficiency measure for any campaign where you can track the value of a sale, which is why it is the go-to number for online stores.
Where cost per acquisition counts conversions, ROAS weighs them by value, so a campaign that wins a few large orders can look far healthier than one that wins many small ones. That extra resolution is useful, but it comes with a requirement: you need conversion tracking that passes real transaction values back to Google, not just a count of conversions. Without that, there is no revenue figure to divide by, and no ROAS.
For a business owner, the trap is treating ROAS as profit. It is not. It measures revenue against ad spend, and it ignores your cost of goods, overheads and every other expense. A four-to-one ROAS sounds strong, but if your margins are thin it can still lose money, while a lower ROAS on a high-margin product can be very profitable. The number that matters is your break-even ROAS, the point where the revenue covers the product and the ad spend, and that depends entirely on your margins.
One more honest caveat: ROAS leans on whatever attribution model your account uses, and no model captures the whole journey. Real buying journeys rarely work neatly, someone might discover you through an ad, then return later via a direct visit or a search for your name. So read ROAS as a strong directional guide to campaign efficiency, not a perfectly precise ledger, and pair it with cost per click and CPA for the fuller picture.
Key points
- ROAS is revenue divided by ad spend, often shown as a ratio like 4:1.
- It weighs conversions by value, unlike CPA, which counts them equally.
- It needs conversion tracking that passes real sale values back to Google.
- ROAS is not profit, it ignores cost of goods and overheads entirely.
- What matters is your break-even ROAS, which depends on your margins.
- Treat it as a directional efficiency guide, attribution is rarely perfectly precise.
Frequently asked questions
Common questions about return on ad spend.
It depends on your margins, so there is no single good number. A business selling high-margin digital products can thrive on a two-to-one ROAS, while a retailer on thin margins might need five-to-one just to break even. The right way to judge it is to work out your break-even ROAS first, the point where revenue covers both your product cost and the ad spend, then aim comfortably above it. A ROAS that looks impressive in isolation tells you very little until you set it against what it actually costs you to fulfil those sales.
They answer different questions. CPA tells you what one conversion costs, treating every conversion as equal, while ROAS tells you how much revenue each dollar of ad spend brought back, weighing each sale by its value. For lead generation, where enquiries are roughly comparable, CPA is usually the cleaner measure. For a shop where order values swing from small to large, ROAS captures something CPA misses, that not all conversions are worth the same. Plenty of accounts watch both.
Because ROAS measures revenue, not profit. It compares sales to ad spend and ignores everything else it costs to run your business: the product itself, shipping, staff, overheads. A four-to-one ROAS on a product with a slim margin can still lose money once all that is accounted for, whereas a lower ROAS on something you make good margin on can be very profitable. Always translate ROAS back into whether the revenue covers your true costs, not just the ad bill.
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