Sometimes, Amplitude's numbers may differ from those provided by other vendors (e.g. Google Analytics, Mixpanel, etc). This can happen for a number of different reasons, several of which we will explore in this article.
Before you begin
This article assumes that you understand how Amplitude tracks users and sessions. If you don't feel confident in your understanding, check out our Help Center articles on tracking unique users and on the definition of a session in Amplitude before proceeding.
Data discrepancy checklist
This list of questions acts as a quick troubleshooting checklist for any data discrepancies you may be experiencing. If you can answer "yes" to a question, it's probably not the cause.
Do the time zones between Amplitude and the other platform align?
If not, be sure to align the time zones before comparing numbers. Data ingested by Amplitude are timestamped in UTC, but you can customize the time zone within our UI.
Do the events you currently track in Amplitude reflect what you're tracking in the other platform?
If not, then a discrepancy between your users and sessions numbers becomes more likely, as both are dependent on the events being tracked.
Do Amplitude and the other platform block the same web bots and scrapers?
If not, then a discrepancy between your users and sessions numbers becomes more likely.
Do the other platform and Amplitude both define the metric of interest the same way?
If not, then it's likely that there will be a discrepancy, since Amplitude and the other platform define the metric differently.
Does the other platform merge users like Amplitude does?
If not, then depending on how the other platform merges its users, you may see a discrepancy between your users and sessions numbers, since the user identification differs.
Is the session timeout window the same between Amplitude and the other platform?
If not, you're more likely to see a discrepancy between your sessions numbers.
Note that if you're tracking data via the Amplitude SDKs, the default session timeout windows are 30 minutes for web and five minutes for mobile. These thresholds are customizable in Amplitude, so please confirm with your developer whether they have been customized.
Sessions in Google Analytics
Though Google Analytics and Amplitude track sessions similarly, this table outlines factors that cause a discrepancy in your session numbers.
| Scenario | Amplitude | Google Analytics | Source |
|---|---|---|---|
| Time hits midnight | Session continues | The current session ends at 11:59 PM and the new session starts at 12:00 AM. | See "Time Based Expiration" |
| Campaign source changes | Session continues | New session begins even if it is within the 30-minute threshold. | See "Campaign Based Expiration" |
| Session Event Limit | No limit | After the first 10 events, tracking is limited to 1 event per second. | See "Events Per Session Limit" |