Conversion Tracking Setup: How to Make Google Ads and GA4 Agree on What a Lead Is

Your Google Ads account says 47 conversions last month. GA4 says 31. Your CRM has 12 enquiries worth answering. None of those systems is lying — they are counting different things, and until you fix that, every bidding decision you make rests on a number you cannot defend.

Conversion tracking setup is the least interesting job in performance marketing and the one that decides whether everything else works. Smart Bidding optimises towards whatever you tell it a conversion is. Define it carelessly and Google will get extremely good at buying you the wrong thing.

Decide what a lead is before you touch a tag

Start on paper, not in an interface. Write down the actions that genuinely move money in your business and rank them. For a lead-generation business that usually looks like: enquiry form completed, phone call answered and held for a minute, quote requested. For ecommerce it is purchase first and nearly everything else a distant second.

Then write down the actions you want to see but never want an algorithm chasing: newsletter signups, PDF downloads, scroll depth, time on page. Both lists matter. The common mistake is not tracking too little. It is treating everything as equally valuable and letting the machine decide which one is cheapest to buy.

If you cannot rank your conversions by what they are worth, you are not ready to run automated bidding. That is not a criticism, it is a sequencing problem. Fix the definition, then spend.

Events, key events and conversions are three different things

Google renamed things and, unusually, the new names reflect the hierarchy properly. In GA4, everything is an event. An event you mark as important becomes a key event, which is reported in Analytics. A key event you want to bid on becomes a conversion in Google Ads. Google's own documentation lays it out as event, then key event, then conversion.

Two consequences people miss. First, only events marked as key events are eligible for import into Google Ads, and after you link accounts or mark an event it can take 24 to 48 hours before the import option appears — so do not conclude it is broken on day one and start rebuilding. Second, conversions created from Analytics arrive in Google Ads set to secondary by default, and can only be promoted to primary inside Google Ads itself.

Pick one source of truth and stop double-counting

You can measure conversions with the Google tag directly, with GA4, or with both. Both is where accounts get messy. The same form submission arrives twice under two slightly different names, both get marked primary, and your cost per conversion halves overnight while your actual enquiry volume does not move at all.

Choose deliberately. The Google tag gives you a dedicated Ads signal and access to enhanced conversions. GA4 gives you cross-channel measurement, so you can see what organic search and email contribute alongside paid. Most accounts we inherit are better served by tagging the money actions directly for Google Ads and using GA4 for the wider picture. The important part is not which you pick — it is that one of them, not both, feeds the bidding.

Set primary and secondary on purpose

This is the setting most often left on autopilot. Primary conversion actions are reported in the "Conversions" column and used for bidding. Secondary actions are observation only and land in "All conversions". Google documents the distinction plainly and warns that misconfiguring it stops Smart Bidding optimising properly.

So: enquiry form and qualified call, primary. Newsletter signup, brochure download, contact-page view, secondary. If you have a long sales cycle and genuinely too few primary conversions for a bidding algorithm to learn from, that is an argument for tracking one mid-funnel action and being honest that it is a proxy. It is not an argument for promoting everything to primary so the column looks healthier.

Give conversions a value, even a rough one

If every lead counts as 1, Google will cheerfully bring you a hundred low-intent enquiries instead of ten good ones and report it as a triumph. You do not need a perfect number to prevent that. Take your average order or contract value, multiply by the rate at which enquiries become customers, and use the result. A plumber who wins one in four £400 jobs has a £100 lead. That is enough to run target ROAS rather than target CPA, and enough to expose the campaign that looks cheap and sells nothing.

Where you can, feed qualification back in. Marking closed-won deals in your CRM and returning that data to Google Ads is the difference between optimising for enquiries and optimising for customers. It takes an afternoon to set up and it changes what the algorithm chases.

Check it works before you trust it

Submit a real test enquiry and watch it appear as a conversion within the delay you expect. Then, every month, compare the reported number against the one source that cannot be gamed: how many real conversations your team actually had. A small gap is normal — modelled conversions and consent choices account for some of it. A gap of several multiples is a setup problem, not a measurement quirk.

We rebuild tracking as the first job on almost every account we take over, because the alternative is optimising confidently in the wrong direction for three months and calling it a test. It is the same reason our CRO work starts with measurement rather than button colours. You cannot improve a conversion rate you are not measuring honestly, and you cannot judge a landing page against a number that counts brochure downloads as sales.

Get this right and everything downstream gets easier. Google Ads bidding has something real to learn from, your monthly reporting stops needing a paragraph of explanation, and you can decide whether a campaign deserves more budget without anyone arguing about which dashboard is correct.

If your conversion numbers do not match your inbox, get in touch and we will tell you where the leak is.