FAQ: Why is the user count of historical dates changing?

  • Updated

The user count for an earlier date can fluctuate as time goes by. When you view your data on different days, the number of users for an earlier date may increase or decrease.

Scenario 1: The user count increases.

This happens when events of an earlier date are ingested into Amplitude later.

Reasons Solutions

Our mobile SDKs batch events. The threshold is every 30 seconds or 30 events.

If the user did not cross the threshold, the events might not get sent until the user comes back to the app and performs more events.

Adjust the frequency at which events are uploaded. 

  • For Android Kotlin SDK, configure flushIntervalMillis and/or flushQueueSize. 
  • For iOS SDK, configure eventUploadPeriodSeconds and/or eventUploadThreshold. 
See our SDK documentation to learn more about configuring the threshold on other SDKs.
Our Batch API/server-side integrations have inherent delays. Do more frequent scheduled batches

The cellular or Wi-fi connection on the user’s device is also important.

If the user performed events but the connection was not there or strong enough, we will also hold onto the events until the connection is strong enough to send.


Unfortunately, there is nothing that we can really do in this case.

Scenario 2: The user count decreases.

The decrease is due to user merging. Amplitude uses a system of User IDs, Device IDs, and Amplitude IDs to track unique users. If not all of your users have User IDs or you have a lot of anonymous events, it's easy for the anonymous events to first have an anonymous profile and then later merge into a known profile. Therefore, two profiles (one anonymous and one known) merge into one known profile. 

Your data will stabilize after a period of time, as anonymous users come back and merge to existing profiles. This period of time depends on your user behavior (e.g. how often they return to your product) as well as your settings (e.g. how often you batch events).

If you have users who come back every day, their events will only have a day in delay, and Amplitude can merge active user profiles faster. If users don't come back very often, then events may be delayed for a long while or Amplitude is not able to recognize and consolidate users as easily.