Why Google Ads and GA4 never agree on your lead count (and which to trust)

It’s one of the most common questions a business owner asks when they start looking at their own numbers: “Google Ads says I got 40 conversions this month, but GA4 says 31 — so which one is lying?” The honest answer is neither. They’re counting different things, in different ways, and they were never designed to match. Once you understand why, you stop chasing a reconciliation that can’t exist and start reading the numbers correctly.

The four reasons they’ll never line up

1. They attribute the conversion to different moments. Google Ads, by default, credits a conversion back to the day of the ad click, even if the person converted a week later. GA4 credits it to the session where the conversion happened. So a click on the 1st that becomes a lead on the 8th lands in different months depending on which tool you’re reading. Over any given period, that alone pulls the two numbers apart.

2. They use different attribution models. The two platforms can apply different logic for which touchpoint gets the credit when there are several. Unless they’re configured identically (and often they can’t be), they’ll assign the same conversions differently.

3. They count differently — “every” vs “unique”. Google Ads can be set to count every conversion from a click; GA4 counts key events its own way. If someone submits a form twice, or converts through two paths, the two tools may tally that differently.

4. They see different people. Ad blockers, consent choices, cookie limits and cross-device journeys affect each platform differently. Some conversions one tool sees, the other simply doesn’t. This isn’t a bug — it’s the reality of measurement on the modern web.

So which one do you trust?

Here’s the part most explanations skip: it depends on the question you’re asking.

• “How are my ads performing, and how should I bid?” — Trust Google Ads. Its conversion data is what the bidding algorithms use, and for optimising campaigns you want the number the system is actually acting on.
• “How does paid stack up against my other channels, and what’s the full picture?” — Trust GA4. It sees all your traffic sources together, so it’s the fairer place to compare paid against organic, direct and the rest.

Trying to force them to match is the wrong goal. Using each for what it’s good at is the right one.

The number that beats both

There’s a third number that matters more than either dashboard: how many of those conversions became actual customers. A platform can only count the form fill or the phone call — it can’t tell you which ones your sales team turned into revenue. The businesses that get the most out of their advertising are the ones tracking conversions through to closed work, not just to the dashboard. That’s the number worth building your reporting around.

None of this means the tools are untrustworthy — it means they need reading, not blind faith. A 40-vs-31 gap is normal and explainable. A gap that suddenly changes — or a tracking setup that’s genuinely broken — is a different problem, and that’s worth catching.

This is the same principle behind the marketing metrics that actually matter and judging whether your Google Ads agency is doing a good job: the goal isn’t a prettier dashboard, it’s knowing which number tells the truth. If your two platforms are disagreeing and you’re not sure whether it’s normal or a real problem, that’s a quick thing for us to check.