When businesses first start running paid advertising, they focus on the metrics that are most visible: clicks, impressions, click-through rate, average cost per click. These metrics are easy to understand and they look important. But they are all upstream of the one number that actually determines whether your PPC advertising is working: return on ad spend, or ROAS.
What ROAS means
ROAS is the revenue generated for every pound spent on advertising. The formula is straightforward: divide the revenue generated by your ads by the amount spent on those ads. A campaign that generates five thousand pounds in revenue from one thousand pounds of ad spend has a ROAS of 5, or 500 percent. That means for every one pound put into advertising, five pounds came back in revenue.
ROAS is the metric that tells you whether your advertising is profitable. Every other metric is a contributing factor to ROAS but none of them, individually, tells you whether the money you spent was worth spending.
Why other metrics mislead you
A high click-through rate is encouraging. It suggests your ads are relevant and compelling enough that people are choosing to click them. But a campaign can have a 10 percent click-through rate and a catastrophically poor ROAS if those clicks are not converting into sales. You are paying for lots of clicks and generating very little revenue from them.
A low cost per click looks efficient. But if those low-cost clicks are coming from keywords with poor purchase intent, converting at a very low rate, a low CPC simply means you are losing money slowly rather than quickly. CPC without conversion context is meaningless.
Impressions tell you how many times your ads were shown. They contribute nothing useful to understanding the financial return on your advertising spend.
What a good ROAS looks like
What counts as a good ROAS varies by business model and product margin. An eCommerce business with a 30 percent gross margin needs a ROAS above 3.3 to break even on advertising alone, before accounting for fulfilment, overheads and other costs. In practice, a ROAS below 4 in that scenario means advertising is eroding rather than building profit.
A service business with higher margins, say a law firm or a consultant, can operate profitably at a lower ROAS because each customer acquired is worth significantly more in net terms. A business generating ten thousand pounds in gross profit per client can afford to spend two thousand pounds acquiring that client and still have an excellent return.
The starting point for any business should be calculating what ROAS you need to break even, then what ROAS constitutes a genuinely profitable return, before running any advertising. Running ads without knowing your breakeven ROAS means you have no way of knowing whether your campaigns are working.
How to improve your ROAS
ROAS improves through a combination of reducing cost and increasing revenue from the same spend. On the cost side: tighter keyword targeting, better negative keyword lists, improved quality scores and smarter bidding strategies all reduce what you pay per click. On the revenue side: better landing pages, stronger calls to action, faster page speed and clearer offers all increase the percentage of clicks that convert into sales or enquiries.
The most reliable way to systematically improve ROAS is to run structured tests: one change at a time, measured over a statistically meaningful period. Change the landing page headline and measure conversion rate. Change the ad copy and measure click-through rate. Change the keyword match types and measure cost per conversion. Each incremental improvement compounds over time into a meaningfully better return.
Track ROAS properly
As with ads that get clicks but no enquiries, ROAS can only be measured accurately if your conversion tracking is set up correctly. If Google Ads is not recording sales or enquiries accurately, your ROAS data is wrong and every optimisation decision you make based on it will be wrong too. Before spending meaningfully on Google Ads, verify that every conversion, whether a form submission, a phone call or a completed purchase, is being tracked and attributed correctly in both Google Ads and Google Analytics 4.
ROAS is simple in concept but only as accurate as the data feeding into it. Get the tracking right first. Then let the numbers tell you what is working.
