Why does conversion data differ between GA4 and Google Ads?
Jakob Twedmark
CEO
Many e-commerce businesses have encountered this problem: why do Google Analytics 4 (GA4) and Google Ads show different conversion numbers? For many, these discrepancies can be confusing, especially when trying to understand how well their marketing is performing.
Let's first examine Google's explanation of what creates these differences between Google Ads and GA4, and how you can use that insight to optimize sales:
Currently, conversion modeling in GA4 is performed independently of that in Google Ads. GA4 only exports the conversions that have actually been observed to Google Ads. Google Ads then applies its own conversion modeling to these observed conversions. It is also worth noting that conversion modeling in GA4 does not affect the total number of reported conversions, while Google Ads may increase this number.
This can lead to differences in the conversions reported by GA4 compared to Google Ads. Additionally, there is no way to turn off modeled conversions in GA4. Modeled conversion data is used when the necessary information cannot be observed. -Google
If you feel equally confused after this summary from Google, you are not alone. Let us therefore break it down and try to understand it better.
What is a conversion?
Let's start with the most important thing — what is a conversion? A "conversion" (Key Event) is when a visitor to your website does something valuable for your business. This could be purchasing a product, signing up for a newsletter, or contacting you. Measuring conversions is important for understanding how effective your marketing efforts are.
So how is a conversion defined in Google Ads and GA4?
Google Ads: Here, a conversion is counted as a specific action someone takes after clicking on an ad, such as buying something, signing up, or visiting a physical store. Google Ads only tracks these conversions if the user actually takes that action after clicking on the ad.
Google Analytics 4 (GA4): In GA4, the definition of a conversion is more flexible. It can take into account the various ways users can interact with your website, and it uses different methods to calculate how users reach your goals. This means that GA4 can provide a more nuanced picture of how different channels, such as social media or newsletters, influence conversions.
Attribution — the key to understanding the effectiveness of your marketing channels
Then there is attribution, which is about identifying which marketing channels generate traffic and sales to the website. When a customer interacts with different marketing channels — such as ads on Google, social media, or newsletters — it is important to understand which channel led to the purchase. Attribution models help us see which marketing is working best.
Google Ads gives all the credit to the last ad the user clicked on. This can cause the number of reported conversions to be higher, since all sales are attributed to the most recent ad.
GA4 uses multiple attribution models, meaning it can give credit to different channels that the user has interacted with before converting. This can provide a fairer picture of how all your marketing channels work together.
Why do differences in reporting occur?
Google Ads and GA4 therefore use different methods to count and report conversions and attribution, which can lead to large differences in the numbers — sometimes up to 100%. Google Ads may report more conversions than GA4, which can give the impression that ads are more effective than they actually are. On the other hand, GA4 may show higher numbers if conversions occur through channels that Google Ads does not register.
If you want to learn more about how conversion modeling works, you can read more about it on Google here: How conversion modeling works
So how should you act?
The differences in reported conversions between GA4 and Google Ads are due to different measurement methods, attribution models, and conversion modeling. When evaluating campaigns, it is therefore important to keep the following in mind:
- Use both platforms: Both GA4 and Google Ads provide valuable information. Use them together to get a complete picture of your campaign's performance.
- Look at the big picture: Focus on total sales and use GA4 to understand customer behaviors and interactions over time, rather than relying solely on ad conversions in Google Ads.
- Analyze attribution models: Be aware that different attribution models can affect how conversions are attributed. Compare results with an understanding of how each platform calculates conversions.
- Monitor trends in the numbers: Instead of only comparing numbers from a specific period, look at trends over time. This can provide a better understanding of how your marketing efforts are affecting sales.
By keeping these recommendations in mind, you can more effectively evaluate your campaigns and make good decisions for future marketing strategies.
