Return on ad spend is the revenue a campaign produced divided by what it cost, expressed as a ratio or a percentage: five pounds of sales for every pound of advertising is a ROAS of 5, or 500 per cent, and the number only becomes a decision once it is compared with the margin on those sales.
Assessment. ROAS is the figure most advertising reports lead with and the one least often compared with the figure that gives it meaning, the gross margin. A campaign returning four pounds per pound spent is highly profitable for a software product and loss-making for a retailer with thin margins; the break-even point is one divided by the margin, and a team that does not know its break-even ROAS is reporting a ratio rather than a result.
The arithmetic is a division: conversion value attributed to the ads, over ad spend. Google's bidding help illustrates it with a shoe retailer that wants five dollars of sales for each dollar of advertising, which is a target ROAS of 500 per cent, and that example also shows the prerequisite: the ads account must know the value of each conversion, from the sale amount on an order confirmation or a value assigned to a lead, before the ratio exists. A campaign with conversions but no values has a cost per acquisition and no ROAS, which is fine for a lead-generation business where every enquiry is worth roughly the same and useless for a shop where one order is worth fifty times another.
ROAS = attributed revenue ÷ ad spend. Says how much came back per unit spent.
Break-even ROAS = 1 ÷ gross margin. A 25 per cent margin needs a ROAS of 4 just to cover the cost of goods and the ads.
Cost per acquisition = ad spend ÷ conversions. The lead-generation equivalent, compared against the value of a customer rather than an order.
Customer acquisition cost = all acquisition spend ÷ new customers. The finance view, with salaries and tools included, compared against lifetime value.
The ratio depends on two upstream decisions it hides. The first is attribution: the revenue in the numerator is whatever the model credited to the campaign, so a brand-search campaign reports a high ROAS under last click and a modest one under a holdout. The second is the window: a campaign judged on the revenue within seven days of the click looks poor for a product people buy after a month of thought, and a subscription business has to decide whether the numerator is the first payment or the expected lifetime. Two teams can report different ROAS figures for the same spend and both be reading their dashboards correctly.
Business
Gross margin
Break-even ROAS
A reported ROAS of 4 means
Software subscription
80 per cent
1.25
Strongly profitable on the first payment alone
Fashion retailer
50 per cent
2
Profitable, with returns still to deduct
Electronics reseller
15 per cent
6.7
A loss on every sale the ads produced
The platforms now bid to the number directly. A target ROAS strategy sets the ratio the advertiser wants and lets the system predict each auction's conversion value and bid accordingly; Google requires at least fifteen conversions in the past thirty days for Search and Shopping campaigns before the strategy can learn, and more for other campaign types. Automated bidding has moved the practitioner's work upstream, to the conversion values, the margin per product line that feeds them and the target that is set, which is where the pay-per-click courses under paid search and display and the Google Ads Measurement certification concentrate.
In practice
A homeware shop reports a ROAS of 3.5 across its shopping campaigns and calls the channel a success. Margin by category shows that candles carry a 60 per cent margin and small furniture 20 per cent; the blended figure hides a profitable campaign and a loss-making one. The targets are split, candles to a target ROAS of 2.5 and furniture to 6, and the system shifts budget toward the auctions it can win at those ratios. Total revenue falls slightly, profit rises, and the report now leads with the margin line it had been missing.
Pay-per-click is the buying model, paying per click; return on ad spend is the measure of what the clicks produced. A campaign can have a low cost per click and a poor ROAS, or an expensive click that returns handsomely.
Conversion rate optimisation improves how many visitors act; ROAS reports what the advertising spend returned. A better conversion rate raises ROAS without touching the campaign, which is why the two are managed together.
Key takeaways
→Revenue over spend, and only meaningful next to the margin: break-even ROAS is one divided by gross margin.
→The numerator is attributed revenue inside a window; change the model or the window and the ratio changes.
→Automated bidding targets the ratio; the work moved to conversion values and margins per product line.
One above the business's break-even point by enough to cover the costs the margin leaves out: returns, payment fees, the team's time. The figure differs by business, which is why published averages are noise; a retailer with a 40 per cent margin needs at least 2.5 and should want more.
Why is ROAS different from ROI?
ROAS divides revenue by ad spend and ignores every other cost; return on investment divides profit by total cost. A campaign with a healthy ROAS can still lose money once goods, fulfilment and overheads are counted, which is what ROI shows.
Can a lead-generation business use ROAS?
Only by assigning a value to each lead, typically the average deal value times the close rate for that lead type. Done with care it works; done with one value for every lead it hides the difference between an enquiry from a decision-maker and one from a student.
Sources
The primary text this definition rests on. Read it before relying on this one.
