What is ROAS?
ROAS, short for return on ad spend, is a marketing metric that measures how much revenue an advertising campaign earns for every pound spent on it. It is calculated by dividing the revenue attributed to the ads by the cost of those ads, and it is usually expressed as a ratio or a multiple, so a ROAS of 4 means four pounds of revenue for every one pound of ad spend. It tells you how efficiently your advertising turns budget into sales, but because it is based on revenue rather than profit, it is a measure of efficiency, not of whether a campaign actually makes money.
ROAS (Return on Ad Spend), explained properly.
How ROAS is calculated
The formula is deliberately simple: revenue attributed to the advertising, divided by the cost of that advertising. Spend two thousand pounds on a campaign that generates ten thousand pounds in tracked sales and the ROAS is 5, often written as 5:1 or 500 per cent. The simplicity is the appeal and also the trap, because every part of that sum depends on decisions that sit underneath it. Which conversions count, over what window, and whether you measure the last click or the whole journey all change the number without changing reality. Revenue is also not the same as margin, and a headline figure that ignores the cost of goods, delivery, returns and fees can look healthy while the campaign quietly loses money. ROAS is best read as one input, defined clearly and used consistently, rather than a single score that settles the argument on its own.
What counts as a good ROAS
There is no universal target, which is the honest answer people rarely want. A good ROAS is one that clears your break-even point with enough room to make the activity worthwhile, and that point is set by your margins, not by a benchmark from another business. A company with a seventy per cent gross margin can thrive on a ROAS that would bankrupt one running on ten per cent, because the second needs far more revenue to cover the same costs. The stage of the customer relationship matters too: acquiring a first-time buyer often looks inefficient on the first sale but pays back over repeat purchases, so judging a prospecting campaign by the same target as a remarketing one usually understates its value. The useful question is not whether a ROAS is high, but whether it beats the point at which the campaign covers its true costs and contributes profit.
ROAS, ROI and profit
ROAS and ROI are related but not interchangeable, and confusing them is where a lot of money goes quietly wrong. ROAS compares revenue to ad spend alone, ignoring every other cost. Return on investment compares profit to total cost, so it accounts for the product, fulfilment, overheads and the fees that ROAS leaves out. A campaign can post a strong ROAS and a negative ROI at the same time if the margin on what it sells is thin. This is why a rising ROAS is not automatically good news and a falling one is not automatically bad: pushing spend towards easy, already-converting audiences can inflate the ratio while adding little genuinely new business, and expanding into fresh demand can lower it while growing the profit that actually matters. The metric to protect is the one tied to money in the bank, and ROAS is a proxy for it, not a replacement.
Why attribution changes the number
ROAS is only ever as trustworthy as the tracking behind it, and tracking has become harder rather than easier. Privacy changes, cookie restrictions, ad blockers and consent choices mean a meaningful share of conversions are now modelled or estimated rather than observed directly, so two platforms measuring the same campaign will often disagree. Each ad platform also tends to claim credit for conversions it influenced, which means adding up the ROAS reported by Google, Meta and everything else can total far more revenue than the business genuinely earned. The attribution window matters as well: a longer window captures slow decisions but risks crediting the ads for sales that would have happened anyway. None of this makes ROAS useless, but it does mean the figure should be read with its method in view. A ROAS quoted without saying what it counted, over what period and against which source is a number without a foundation.
How ROAS connects to bidding and AI-driven ads
Modern ad platforms let you hand ROAS to the machine as a target and have the bidding optimise towards it automatically, which is powerful and easy to misuse. A target ROAS strategy tells the platform how much revenue you expect per pound, and its algorithms then chase that goal within the budget and signals you provide. The catch is that the system optimises for exactly what you tell it, so a target set too high starves the campaign of volume, and one fed poor conversion data optimises confidently towards the wrong outcome. As more of this decision-making moves to automated and AI-driven systems, the human job shifts from setting bids by hand to feeding the platform clean data, honest conversion values and a target grounded in real margins. Get those inputs right and automation compounds them; get them wrong and it compounds the mistake just as efficiently. The metric still needs judgement behind it, which is why we treat target-setting as a decision, not a default.
ROAS (Return on Ad Spend): common questions.
What is ROAS in simple terms?
It is how much revenue your advertising earns for every pound you spend on it. Divide the sales you can attribute to a campaign by what the campaign cost, and you get the return on ad spend. A ROAS of 4 means four pounds of tracked revenue for each pound spent. It is a quick read on efficiency, but it counts revenue rather than profit, so a good-looking ROAS does not always mean the campaign is making money.
How do you calculate ROAS?
You divide the revenue attributed to the advertising by the cost of that advertising. Ten thousand pounds of sales from two thousand pounds of spend is a ROAS of 5, or 5:1. The sum is easy, but the inputs are where the care goes: which conversions you count, over what attribution window, and from which data source all change the answer, so it is worth defining those clearly and keeping them consistent over time.
What is a good ROAS?
There is no single right number, because it depends on your margins. A good ROAS is one that clears the point where the campaign covers its true costs and still contributes profit, and that point is far lower for a high-margin business than a low-margin one. Prospecting campaigns aimed at new customers also tend to show a lower ROAS than remarketing, so the same target should not be applied to both.
What is the difference between ROAS and ROI?
ROAS compares revenue to ad spend alone and ignores every other cost. ROI compares profit to total cost, so it accounts for the product, fulfilment, overheads and fees that ROAS leaves out. Because of that gap, a campaign can post a strong ROAS and still be unprofitable on ROI when margins are thin. ROAS is a useful proxy for efficiency, but ROI is the measure tied to money the business actually keeps.
Why do different platforms report different ROAS figures?
Mostly because of attribution. Each ad platform tends to claim credit for conversions it influenced, and with privacy changes and consent choices a share of conversions is now modelled rather than observed directly. That means Google, Meta and your analytics can all report a different ROAS for the same activity, and adding them up can overstate real revenue. It is why a ROAS should always come with the method behind it rather than being taken at face value.