In one sentence: Return on ad spend is the revenue an advertising campaign produced divided by what that campaign cost, usually stated as a ratio such as 4 to 1, meaning four dollars of revenue came back for every dollar spent.
Return on ad spend answers one question: for every dollar handed to the platform, how many dollars came back as revenue? Take the revenue you can trace to the campaign, divide it by what the campaign cost. That is the entire formula.
What it leaves out is everything between revenue and profit. As a worked example, say a campaign costs $1,000 in a month and the jobs it brought in billed $5,000. That is a 5 to 1 return on ad spend. If materials, crew time and the truck on those jobs ran $3,500, the campaign left you $500 once the ad bill was paid, which is a very different sentence than 5 to 1.
The ratio also says nothing about what the revenue cost you to deliver. Two campaigns posting the same number are not the same campaign if one sells a job you finish in an afternoon and the other sells one that ties up a crew for a week.
Both figures are real. Only one of them pays you.
An online store hands the platform a dollar value at checkout, so the reporting fills itself in. A roofer, a dentist or a dock builder gets no such gift. The platform sees a form submission or a phone call and has no idea whether that call turned into a small repair or a full replacement.
So the honest version for a service business gets built backwards. You decide what a booked job is worth, you send that value back to the platform when a lead actually closes, and only then does the ratio mean anything. Until that loop exists you are reading ad cost against phone calls, which is a different metric wearing this one's name.
Wiring that loop up is part of the job in Google Ads management. A storefront with over 1,400 products and live Stripe checkout, built for a Virginia retailer, reports its order values on its own. Most service accounts have to be told what a job is worth.
There is no universal target. A business running thin margins needs a far higher ratio to break even than one running fat margins, and a business that keeps customers for years can afford to lose money on the first sale. Anyone who quotes you a number without asking about your margin or your repeat rate is guessing.
Work out your own floor instead: the ratio at which a campaign covers the goods, the labor and the management fee and still leaves something behind. Above the floor, you can afford to spend more. Below it, volume is not your problem.
Decide which revenue counts before you start, too. Some accounts credit the first job and stop there. Others credit the first job plus what a customer typically spends over the year that follows. Both are defensible, and a number built one way tells you nothing when you hold it next to a number built the other way. Pick one, write it down, and keep it.
Because a small campaign is usually showing on only the handful of searches from people who were already going to call you, and those come back cheap. Opening it up usually lowers the ratio and raises total profit. The ratio measures efficiency, and efficiency trades against volume, so the best number in the account is rarely the campaign putting the most money in your pocket.
The platform's version does not, because it counts media spend only. If the question you are really asking is whether marketing is worth doing, add the management fee to the bottom of the fraction so the number reflects every check you wrote. Ads management is commonly billed either as a flat monthly fee or as a percentage of spend, and we quote a flat fee after a free consult.
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