ROAS measures how much revenue you earn for every pound or dollar you spend on advertising. If you spend £1,000 on Google Ads and generate £5,000 in revenue, your ROAS is 5:1. It is the single most referenced metric in paid media, and also one of the most misunderstood. A high ROAS does not automatically mean a profitable campaign, because it says nothing about your margins, your lifetime value, or your attribution accuracy.
ROAS gives you a direct line of sight between ad spend and revenue, which makes it the metric most budget decisions are built on. Get it right and you can confidently scale campaigns that are actually making money. Get it wrong, and you will either starve profitable campaigns of budget or keep pouring money into ones that look good on a dashboard but lose money at the bank.
The formula is simple: revenue from ads divided by cost of ads. A £10,000 campaign generating £40,000 in revenue gives you a 4:1 ROAS. The complexity is in what counts as revenue. Are you measuring first-purchase revenue only, or including repeat purchases? Are you crediting the right touchpoint? Most platforms report their own version of ROAS, and they are always generous with the attribution. You need to reconcile platform-reported ROAS with your actual backend data before making any scaling decisions.
The biggest mistake is treating ROAS as a profit metric. A 3:1 ROAS on a product with 25% margins means you are breaking even at best. The second most common error is comparing ROAS across channels without normalising for attribution models; Google and Meta will both happily take credit for the same conversion. We have audited accounts where the combined platform-reported revenue was 180% of actual revenue. If your ROAS targets are not built from your unit economics, they are just vanity numbers.
The questions worth asking before you build your next media plan around a ROAS target.
There is no universal benchmark, because ROAS targets depend entirely on your margins, customer lifetime value, and business model. A subscription business with 80% gross margins can be profitable at 2:1 ROAS. A product business with 30% margins might need 5:1 or higher. The right target is the one built from your actual unit economics, not an industry average pulled from a blog post.
Google Ads uses its own attribution model and conversion window, which almost always inflates reported performance. Your analytics platform likely uses a different model and may deduplicate conversions across channels. The gap between the two is normal, but if you are making budget decisions based on platform-reported ROAS alone, you are probably overinvesting in whatever Google takes credit for.
It depends on your growth stage and margin structure. Optimising purely for ROAS tends to shrink your campaigns down to only the cheapest, highest-intent traffic. That looks efficient on paper but caps your growth. Most mature advertisers use ROAS as a guardrail, not a goal, and focus on maximising profitable revenue within an acceptable ROAS band.
We build ROAS targets from your P&L, not from platform benchmarks. That means we know your break-even ROAS by product line before a single campaign launches. We also reconcile platform data against backend revenue weekly, so the numbers you see in reports reflect what actually hit your bank account. When we leave, your team knows how to do the same.
ROAS is fundamentally a direct-response metric. Applying it to brand awareness campaigns will either make those campaigns look like failures or force you to attribute revenue they did not directly generate. Brand campaigns are better measured through lift studies, search volume growth, and aided recall. Trying to force every campaign into a ROAS framework is how good brand strategies get killed by spreadsheet logic.
