GA4 was built to track behaviour. It watches how people move through your website. Where they land, what they click, and where they drop off. GA4 comes with standard event tracking, but to track conversions properly, your marketing agency should have set up custom conversion tracking. This can be for goals like completing a form for a purchase, or attending an event, or downloading a gift. What it doesn't know is whether that person actually paid, showed up or accessed the gift.

Google Ads is designed to show its value in your marketing mix. It counts a conversion for itself whenever someone clicks an ad and later completes a goal, as long as it's within a certain time frame. For example, if someone clicked a Google Ad three weeks ago and then converted today after seeing you on Instagram, Google Ads will still take credit. This does depend on how attribution has been set up, as the default is last click.

Your payment system or CRM records what actually happened. Someone purchased, or cancelled, through your ecommerce site or through your booking platform. It may record the source - Google Ads, Facebook, email, search etc, but most payment platforms are not set up to record this accurately.

Each platform has a different job, so you get different numbers. None of them are wrong.

Why reconciling them is the wrong goal

Take this scenario.

You notice Google Ads is reporting 47 conversions this month. GA4 shows 38. Your booking system shows 29 confirmed reservations. So you start asking: which one is right? You loop in your marketing agency. They loop in the developer. Someone suggests updating your tracking setup. A week later, the numbers still don't agree.

The numbers will never match because each platform measures things differently. Their attribution models, tracking periods, and logic all vary. No amount of tweaking tags or pixels will fix this.

The goal isn't to make the numbers match. It's to know which number to trust for each decision.

Choose your source of truth by goal

This practical change makes a big difference. Rather than trying to match numbers, give each platform a clear role and use it that way.

For ecommerce businesses - check your ecommerce platform (Shopify, WooCommerce, Square etc) for purchase numbers and revenue.

For event or accommodation businesses - check the transactions through your booking platform.

For service businesses - check your CRM. All lead capture through forms will be automatically entered into your CRM if this has been set up properly for you. All phone call enquiries should be entered into your CRM manually. You should also be tracking lead to sales conversion in your CRM or in a spreadsheet. (We provide a free leads and sales tracking template to help you do this).

For marketing performance, use GA4. To measure where your business is coming from so you can track the effectiveness of different marketing campaigns, GA4 is your guide. Use it to spot trends and compare channels, not for exact conversion numbers.

For paid channels. Google Ads data is best used within Google Ads. It's the right tool for adjusting bids, comparing ad sets, and seeing what's happening within your paid search. The same applies to Meta Ads tracking. Do not rely on their conversion numbers.

A simple way to think about it:

• Revenue tracking → the payment platform
• Lead tracking → your CRM
• Marketing performance → GA4
• Paid search optimisation → Google Ads or Meta Ads

When you give each platform its own job, tracking and measurement become much clearer and make more sense.

Accept the gap and document it

A 10-20% difference between platforms is quite normal.

We recommend keeping a note in a spreadsheet or a doc of the differences. After a while you will see the pattern and understand the normal variance - eg: "GA4 usually runs about 15% higher than confirmed bookings or sales - that's our normal range."

If the difference suddenly jumps to 40%, that's a sign that something is wrong. It might be a broken link, a tracking and measurement mistake, or a platform problem. It should be relatively easy to find the issue and fix it.

The real fix is to record and analyse the numbers

For more confidence in the ROI of your marketing, it's best to accept the purpose and limitations of each system, and record and analyse results yourself, or have your agency do it for you.

Choose a source of truth for revenue, one for leads, and the most relevant ones for marketing measurement and record the results. Once you have this framework, you stop trying to match numbers and start making better decisions with the data you already have. If you want to try this out, our ROI calculator is a helpful next step. It lets you measure campaign results against the numbers that really matter for your business.