Misunderstood Metrics: New vs Returning Visitors

Why do New + Returning Visitors add up to more than the total Users? How can I have more New Users than Users who are ‘New Visitors’? This Misunderstood Metrics article explores the Behavior > New vs Returning report in Google Analytics, and why the numbers can be confusing.

What is a New User in Google Analytics?

First, let’s clarify how Google Analytics identifies a “New User”: when a visitor views your website, Google’s tracking snippet looks for an existing tracking cookie on the device.

If there is no tracking cookie, then Google creates one and considers this a new visitor to your site. A session is started and the User Type dimension is set to “New Visitor”. All the subsequent hits (pageviews, events, etc) are recorded with this “New Visitor” label.

If there is an existing tracking cookie on the device, then Google starts a new session with the User Type set  to “Returning Visitor”.

Bad Math: Never Total The Users Metric

The first problem people encounter is that the total number of Users (9,947) is lower than the sum of the New Visitors and Returning Visitors (9,167 + 2,254 = 11,421). This is because it is common for a single User to visit your site multiple times during the reporting period. They can be BOTH a ‘new’ and a ‘returning’ visitor — new on Monday, but returning on Tuesday and Wednesday.

Never add up User numbers for a total — the total will almost never match. This is the same as adding daily numbers and comparing it to a weekly or monthly total — Users can visit multiple times during that period and you would count them multiple times.

Further Reading: Google Analytics Users

Tracking Quirks: ‘New Visitor’ Users Do Not Equal ‘New Users’

Another confusing thing is when the number of “New Visitor” Users (9,167) is different from the “New Visitor” New Users (9,276) in the same report…on the same row. It typically appears with websites with global appeal, and on multi-day reports. How can you have more New Users than Users?

This is caused by a quirk of Google Analytics tracking: at midnight, all active sessions are restarted for the new day (see the image below). I think this was historically done so the sessions count would be accurate for each day. Sessions are made up of a series of hits (page views), and the Session is counted only on the first page view of the session — that made reporting easy because a quick total of Sessions and Pageviews would be correct.

That created a problem if a session spanned 2 days, because it would only be counted on the first day, so they decided to restart any active sessions at midnight thinking that would be a good compromise. Reporting was fast and the numbers were pretty close because very few people were surfing the web at midnight.

Over time, they added the “New User” metric, which was calculated as Users that had a ‘hit’ that was tagged as a “New Visitor”.

In the image below, we follow one user’s session that crosses over midnight. from 23:59 through 00:06. If you look at the individual page views, you can see the Sessions and New Users metrics both get re-counted after midnight.

If you summarize by Date, you still see 1 Session, 1 New User and 1 User per day, but if you remove the Date  and look at the whole 2-day period, Google Analytics shows you that there was actually only 1 User; Sessions and New Users still show a count of 2 because of how they are measured.

Tracking Quirks: Sessions Might Be Different Too

If you go back and look at the sample report once again, you will notice that the Sessions for the New Visitors (9,229) do not match the New Users (9,276) or the Users (9,167) numbers. This can happen if you track events in your website, and it is caused by the subtle difference in how New Users and Sessions are counted.

A New User is counted by a ‘hit’ after midnight, but the Session is counted only on the first ‘pageview’. Usually sessions include both, but if a session has pageviews before midnight but only events after midnight, then the Session will not be counted on the second day but the New User will. This scenario can happen more often if you track page scrolling or time-on-page as events.

What Number Should You Use?

If you want a count of total Users, use the total at the top (9,947).

If you want the number of new visitors to your site, use the Users metric in the New Visitors row (9,167).

The difference between New Visitor Users and New Users (9,167 and 9,276) gives you an idea of how busy your website is at midnight, but that’s about it.

You should not use the New Visitor Sessions or New Users numbers for reporting purposes.

Note that the Users metric is approximate (Google uses an algorithm to quickly approximate the count on busy sites), easily affected by sampling and browser anti-tracking options.
Related Articles:
Learn How: Meaningful Metrics: Users
Free Report: New vs Returning Report for Google Analytics
Free Report: Returning Users Report for Google Analytics

Further Reading: Sessions for Pages, Bounce Rate, Users, Frequency/Count of Sessions, Custom Dimensions, Events, Time on Page/Avg Session Duration, Next Page Path