Your GA4 lead numbers are probably too low

Your lead numbers might be wrong, and the awkward part is you would never know from looking at the dashboard. Google Analytics does not flash a warning when it misses an enquiry. It shows you a smaller number, and you carry on making decisions off it. We ran into this on our own site last week: a real enquiry came through the form, landed in the CRM with a timestamp, all good, and GA4 recorded nothing. Not the form event, not even a page view. The visitor’s browser had quietly blocked the analytics tag, so as far as GA4 was concerned, that person never existed.

The lead was real. The form worked. The money was on the table. And the tool most owners use to judge whether their marketing is working recorded a zero. Here is what is going on, what it costs you, and a check you can run yourself in about ten minutes.

How an ad blocker stops the count

Google Analytics works by loading a small script in the visitor’s browser. When someone lands on your site or submits a form, that script sends a message back to Google saying this happened. Your reports are built from those messages.

The catch: that message goes to a Google address that sits on every ad blocker’s block list. So if the visitor is running an ad blocker, a privacy browser, or shields of any kind, the browser refuses to send the message. The form still submits, because that is your site talking to your CRM. The analytics signal never leaves the visitor’s device.

Ad blockers hide one in three visitors

This is not a fringe setup any more. Around 31% of Australian internet users aged 16 to 64 regularly use ad blockers, so call it roughly one in three. The figure jumps to 37% on desktop and sits under 10% on mobile, which matters because the office laptop you would naturally test from is exactly where the blocking lives.

These are three separate populations, all internet users, desktop users and mobile users, so each gets its own part-to-whole donut rather than sharing one pie. The blocked slice is what matters: the visitor most likely to block your tag is on a desktop, which is also where most owners run their own test. Test from a phone on mobile data and you see what your customers actually trigger. Figures: GWI 2024 to 2025.

How much GA4 misses

So how much does GA4 actually miss? The most careful study I have seen comes from Andy Crestodina at Orbit Media, who compared 33 GA4 accounts against their real source-of-truth data, meaning CRMs, email tools and sales records. Sites without a cookie consent banner were missing about 11% of their data, and sites with a banner about 20%. It climbs to 30% or more on tech-savvy or younger audiences who block more aggressively.

A low gauge moves real money

A gauge that reads low is not harmless. You make real decisions off it. Say you are running Google or Facebook ads. You look at GA4, see a campaign that only generated a handful of leads, and you turn it off or cut its budget. GA4 was blind to a chunk of those leads. The campaign might have been your best performer, and you just killed it based on a number that was never complete.

It gets sneakier. Firefox and Safari strip the small tracking codes (gclid and fbclid) that tell GA4 a visitor came from a paid ad, so some of your paid traffic shows up as Direct even when the conversion did fire. Now your ads look worse than they are, your branded-search bucket looks better than it is, and you shift budget the wrong way. The fix is not to bin Google Analytics. It is to know its blind spot and stop treating it as the final word on how many leads you got.

The 10-minute check

You do not need a developer for this. You need a phone and ten minutes. The point is to run a clean test, meaning a test from a device and network that is not quietly blocking anything. Your work laptop is the worst place to test from, because that is exactly where the ad blocker lives.

Now read the result.

• CRM has it and GA4 has it. Tracking is working end to end. Good.
• CRM has it but GA4 shows nothing. Your form works, but your analytics is being blocked or set up wrong. This is the trap we hit, and blocking is eating your numbers.
• Neither has it. The form itself is broken, which is the most urgent of the three. Fix that first.

If you want a stress test, repeat step 1 from your normal work laptop (ad blocker and all) and compare. If the laptop submit does not show in GA4 but the phone one did, you have just watched the undercount happen in real time.

Set the form submit as a key event

A form submission should be a GA4 key event so it gets counted properly in your reports. Google’s own recommended name for it is generate_lead, defined as when a user submits a form or a request for information. You set this up through your tag manager (GTM is common) or through your CRM’s own tracking, then mark it as a key event in GA4. One caution: GA4’s auto-detect feature fires a generic form_submit on every form, including your search box and footer signup, so it is too broad to trust as a lead count. Tie a specific generate_lead event to your actual enquiry form. Marking something as a key event is not backdated either, so the sooner it is set up correctly, the sooner your reports mean something.

The durable fix

The self-check tells you whether you have a problem. Fixing it properly comes down to two things. First, treat your CRM as the source of truth for whether the lead arrived, because it sits between your site and you and catches the enquiry regardless of the visitor’s browser settings. GA4 is for understanding where leads came from, not for the final headcount.

Second, for the tracking itself, the durable answer is server-side tagging: instead of the visitor’s browser sending the analytics signal (where an ad blocker can stop it), the signal goes through your own website’s address and your server forwards it on, so far more of your data gets through and paid-traffic attribution holds up longer. Stape.io is one option built for smaller businesses. It is a real setup rather than a checkbox, so it is worth getting help with. If you would rather sidestep the problem than engineer around it, Plausible Analytics is a privacy-first, cookieless tool that is far less likely to be blocked than GA4, so it tends to capture more of your traffic out of the box. It will not replace everything GA4 does, but for a clean headcount of visitors and conversions it is a strong option.

If reading this made you unsure whether your own numbers are honest, that is the right instinct, and a quick discovery call is the fastest way to find out where you stand. Book a call below.