How to measure the return on your Google and Meta advertising (CAC, ROAS and conversions)

Spending on ads without measuring is like putting coins into a machine without seeing what comes out. Measuring well is not complicated, but it must be set up before you start.

The metrics that matter (and those that matter less)

• Conversion: the action you care about (purchase, quote request, call). It is the basis of everything.
• CPA / CAC (cost per acquisition): what it costs you to get a conversion or a customer.
• ROAS: revenue generated for every euro invested in advertising. A ROAS of 4 means 4 € of sales for every 1 € spent.
• Margin: ROAS alone is misleading. You have to calculate how much of those sales is profit.

Clicks, impressions and likes are intermediate indicators. They help diagnose, not decide whether the campaign works.

Calculate your break-even point

Before launching, answer these questions:

1. How much profit does a sale or a customer leave you (after costs)?
2. What is the most you can pay to win one without losing money?

If a customer leaves you 100 € of margin, you cannot pay more than 100 € to win them. That ceiling is your maximum CPA; if you also want profit, the target must be quite a lot lower.

Set up conversions correctly

In Google Ads

• Import conversions from Google Analytics 4 or install the conversion tag.
• Mark as primary only those that represent business (purchase, form), not “visited the page”.
• For ecommerce, also send the value of each purchase.

In Meta Ads

• Install the pixel and, if possible, the Conversions API to receive events from the server.
• Verify the key events: ViewContent, AddToCart, InitiateCheckout, Purchase or Lead.
• Use event IDs to avoid double-counting conversions.

Name every campaign: UTM

Add UTM parameters to links (utm_source, utm_medium, utm_campaign, utm_content). That way you will know in your analytics which specific ad brought each visit, and not only what the platform says.

The attribution problem

Each platform attributes conversions to itself. It is common for Google, Meta and your analytics to add up to more sales than there really are. Some tips:

• Always compare with the real figure from your shop or CRM.
• Use an attribution window consistent with your buying cycle.
• Look at trends over weeks, not single days.

When a campaign is profitable

A campaign is profitable if the real CPA is lower than the margin each customer leaves you, with enough volume to be stable. Avoid deciding on small samples: with few conversions the data swings a lot.

What to do with the results

• If the CPA is high and there are clicks but few conversions, the problem is usually the website, not the ad: speed, clarity of the offer, form or checkout.
• If the CPA is good, scale gradually (increases of 20–30 % every few days).
• Pause what does not work and move the budget to what does.

At IMPERA 360 we manage your campaigns by setting up measurement first, so every decision is backed by real data.