Why is Amplitude "missing" some events compared to GA4, with same GTM implementation?

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I can’t figure out an issue I’m having: Amplitude is not accounting for all the events I’m tracking in GA4. So, my funnels are completely off.

My configuration is the following:

  • I have an ecommerce site on wordpress, and I have Google Tag Manager set up on it
  • The site “shoots” events to the data layer, following the GA4 logic / syntax (so, triggered simply on all events that match the regex: “view_item|view_item_list|select_item|add_to_cart|remove_from_cart|view_cart|begin_checkout|add_payment_info|add_shipping_info|purchase”
  • GA4 is configured to init on all “Page View” in GTM, and trigger a GA4 event on all events that are shot by the site to the data layer, so that they end up posted in GA4

And all of this is working fine.

To set up Amplitude I did the following:

  • Used the GTM Template
  • Did the “init” the same as for GA4: on every “Page View”
  • Did the posting of the events the same as for GA4: same trigger (so, on all events “view_item|view_item_list|select_item|add_to_cart|remove_from_cart|view_cart|begin_checkout|add_payment_info|add_shipping_info|purchase”)

Even though it’s the same configuration, over a given period of time I get way fewer “users” on those events (like 20 times less users purchasing on Amplitude). So, it’s not that I’m not getting the events, either I’m not getting all of them, either some of the users are “screened”. That’s very very weird.

Any ideas?


Best answer by eddie.gaona 4 April 2023, 23:52

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Userlevel 6
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Thanks for sending these details @nblaisot. Were you able to make progress? We recently released this helpful overview to set up our GTM template. Let us know if you need some additional help! 


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No I haven’t been able to make progress so far. I’ll have a look at your link, thank you! But for now my funnels in GA4 seem to make more sense than the ones in Amplitude

Userlevel 2
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Hey @nblaisot : Is your implementation entirely data layer events for GA4 or are you using Enhanced Measurement as well? Just trying to get a better understanding of your implementation :)

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My implementation is like the one for GA4 so relying entirely on data layer events. I do not know what “Enhanced Measurement” is/means actually :/ 

Userlevel 2
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@nblaisot : How is the site shooting events to the data layer? 

Userlevel 6
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Thanks for jumping in @r0bbieWa11ace 😀

@nblaisot Do you need additional support?


We are having a similar problem (but for all events). In general we see about 70% FEWER users in total than we are seeing in GA4. Did you guys figure this out?

Userlevel 6
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Thanks for posting here @alexp_velada. I’ll make sure that our support team is aware that you’re experiencing this issue. 

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There can be differences in DAUs and other metrics for multiple reasons such as instrumentation or how a daily is defined. We calculate active users at a user level and not device level. Also, we are able to merge anonymous users to when they log in instead of having two separate users. So, for example, if a user was on 2 devices and then logged on (was assigned a User ID) on both devices, then we are able to merge those to a single user. That actually reduces the daily active user count but makes it more accurate. Here is some more documentation on how we track unique users:


Here is a link to other data discrepancy possibilities:


I don’t think that this example applies to us as you can only access our product via the app and it’s unlikely users are accessing us via two phones because most people don’t have two phones, but even so, the discrepancy would not be so large as to be missing 70% of our users. We are looking into the other data discrepancy possibilities...

Hi all,

I was so glad to see this post, did any of you ever find a solution? 
I’m also running into this issue. Both GA4 and Amplitude are connected to my website using the same GTM event tracking settings. But I’m seeing over 90% *fewer* website visitors in Amplitude than in GA4. I’m new to Amplitude so it’s highly possible something’s set up wrong, but I can’t figure out what. 

And yeah, I’ve read both articles that eddie.gaona posted. Unfortunately doesn’t seem to fix the issue.