Why is there a difference in conversions’ count between Meta and analytics solutions?

Key takeaways

Meta can report far more conversions than analytics solutions, with gaps sometimes exceeding 90%, always in Meta's favour.
Post-view attribution explains much of the gap: 72% to 96% of Meta conversions were 1-day post-view conversions.
Meta counts clicks while analytics solutions count sessions, so closed windows and refused cookies create further discrepancies.
Cross-device tracking and modeled conversions for iOS users who opted out via ATT are counted by Meta but not by analytics tools.
Keep only post-click attribution in Meta, count conversions by tracker or rule but not both, and add the Conversion API.

In short

Meta and analytics solutions count conversions differently: Meta includes post-view conversions, counts clicks rather than sessions, tracks cross-device journeys and models conversions for iOS users who opted out. Configuration errors, such as missing tracking codes, redirects to other domains or duplicate counting, widen the gap further. Removing post-view attribution and checking Meta's setup brings the figures closer.

Origin

The origin of this analysis comes from an observation: the number of Meta conversions counted by the analytical solution is much lower than the number of conversions counted by Meta. This difference can be more than 90%, always in favour of Meta according to Meta interface.

This problem could be identified because TrackAd aggregates the information from the traffic sources – Meta in this case – and the analytics solution in the same interface.

Analysis

Meta attribution

The first thing we checked was the attribution configuration in Meta.

We found that for all users with a big difference, the attribution set at Meta level contains Post view tracking.

This explains a difference because the analytics solution does not bring up the post view information from Meta.

In order to understand how much of the conversions tracked by Meta are Post view and Post click, we used the TrackAd connector to retrieve the number of Post view conversions and Post click conversions through API. This attribution analysis, which used to exist directly in Meta, is no longer available.

In our analysis we did not use the Last Click attribution of the analytics solution, but the presence of Meta in the conversion paths, brought up by TrackAd using the tracker of the analytics solution.

This number is close to the notion of Post click of Meta.

The results that emerge are:

From 72% to 96% of Meta conversions consist of 1-day post view conversions
The participation reported by TrackAd corresponds to 70% of the Post clicks identified by Meta in the best case and 30% in the worst case

Data verification

The 30% to 70% difference between the conversions tracked by Meta and by the analytical solution is still too high to be considered normal.

We went further in the analysis to find additional reasons for these differences.

Here are some of them:

There are campaigns in Meta that do not redirect to the main site tracked by the analytics solution but to another domain name. In this case, the resulting conversions are counted by Meta but not by the analytics solution, because it is not the same site.
There are missing tracking codes in the redirection from Meta. Therefore, the analytics solution does not identify Meta as the source of the traffic.
Meta counts clicks while the analytics solution counts sessions. This means that a click on a link in Facebook or Instagram will always be counted by Meta. But if the user closes the window before the analytics tracker is called, the session will not be counted by the analytics solution. The same applies to users who do not allow cookie tracking: their clicks are counted by Meta, but their sessions are not counted by the analytics solution.
Meta tracks conversions that were generated on a device where the user is logged in and finalized on another device. Whereas an analytics solution will not associate this conversion with Meta. We have made an estimate of the share of conversions affected by this scenario but Meta seems to have removed access to this information.
Meta is capable of tracking conversions that are initiated on one device where the user is logged in, and completed on another device, even if the user is not logged in on that second device. This kind of cross-device tracking is not captured by traditional analytics solutions, which are unable to link these steps together. As a result, Meta’s impact as a journey initiator is underestimated. This leads to a biased perception of its incrementality, which is actually higher than what measured data suggests.
Meta uses an Aggregated Event Measurement (AEM) system that includes modeled conversions for iOS users who have opted out of tracking via ATT. These conversions are not visible in analytics solutions and are probabilistically estimated by Meta.
Meta can count the same conversion multiple times if the conversion tracking event is misconfigured. Since it’s not possible to export conversion IDs from Meta, the impact is impossible to quantify. Therefore, it’s important to verify this event. The error may stem from counting a Meta conversion both via a “rule” (e.g., the page URL contains “thank-you”) and via a “tracker.”

Advice

Here are the actions we recommend to implement to reduce the difference between the conversions counted by Meta and those counted by your analytics solution:

Change the conversion attribution settings in Meta to remove Post-view and retain only Post-click.
Check how conversions are counted in Meta: either by tracker or by rule, but not both simultaneously.
Set up a custom event in Facebook and Instagram called “tracked conversions” and trigger this event when a conversion occurs.
Implementing Meta Conversion API (CAPI), in addition to the Pixel, helps ensure more reliable conversion tracking, especially for iOS users or in cookie-less environments.
It is essential to configure priority events in AEM and use the Events Manager to diagnose potential errors.
Check the quality of the traffic. Based on data from numerous advertisers, we’ve observed that Meta generates traffic with a high rate of new visitors and bounce—sometimes three times higher than the site average. This can significantly affect conversion path tracking.
Ensure that the redirects entered in Meta are properly set up. They must point to your website, include correctly formatted tracking codes (no spaces), link to working pages, and have a functioning tracker on each of them.

Meta conversion discrepancies in 6 questions

Why does Meta report more conversions than Google Analytics or my analytics tool?

Meta's attribution settings often include post-view tracking, which analytics solutions cannot see. In the analysis, from 72% to 96% of Meta conversions were 1-day post-view conversions. Other factors, such as the difference between clicks and sessions or cross-device tracking, add to the gap.

How big is the gap between Meta post-click conversions and analytics data?

The participation of Meta reported by TrackAd matched 70% of the post-click conversions identified by Meta in the best case and 30% in the worst case. This remaining difference is still too high to be considered normal. It led to looking for additional causes beyond post-view attribution.

Why do clicks in Meta not always turn into sessions in analytics?

Meta counts every click on a Facebook or Instagram link, while the analytics solution counts sessions. If the user closes the window before the analytics tracker is called, no session is recorded. Users who refuse cookie tracking are also counted by Meta but not by the analytics solution.

What is Aggregated Event Measurement in Meta?

Aggregated Event Measurement (AEM) is a Meta system that includes modeled conversions for iOS users who opted out of tracking via ATT. These conversions are estimated probabilistically by Meta and are not visible in analytics solutions. Configuring priority events in AEM and using the Events Manager helps diagnose errors.

Can Meta count the same conversion twice?

Yes, if the conversion tracking event is misconfigured, Meta can count the same conversion several times. A common cause is counting a conversion both via a rule, such as a URL containing "thank-you", and via a tracker. Because conversion IDs cannot be exported from Meta, the impact cannot be quantified, so the event must be checked.

How can I reduce the discrepancy between Meta and my analytics solution?

Remove post-view from Meta's attribution settings and keep only post-click. Implement the Meta Conversion API alongside the Pixel, and make sure redirects point to your website with correctly formatted tracking codes and a working tracker on each page. Checking traffic quality also helps, as Meta traffic can show high new-visitor and bounce rates.