Users vs Sessions, how to avoid looking at conversion rates that can be 85 % wrong

Erik Öhlén

The conversion rate that you use today might be up to 85 % wrong compared to what you actually want to look at (more examples will follow below). Therefore, it is important to know WHAT you want to look at and WHY. Google Analytics displays several numbers that can look drastically different from what you’re trying to improve CRO wise.

In this post, we want to clarify the differences between the Sessions and User levels. You’ll get a sneak peek of what goes on underneath the GA hood, WHAT you can base your conversion rate on and HOW to get the right numbers if you don’t have them already. The difference between the Sessions and User level is also relevant for other analysis tools, such as Adobe Analytics.

Let’s go!

Do you look at your conversion rate as it is displayed by default in Google Analytics?

Probably not your conversion rate

Okay, but what about Ecommerce tracking?
Probably not your conversion rate either

For several types of conversion goals, these can be ok or even the best conversion rates to look at. The two metrics that are displayed in the conversion rate reports above, “Goal Conversion Rate” and “Ecommerce Conversion Rate”, show how many % of visits (Sessions) that included some form of conversion.

But in most cases, you’re more interested in the % of unique visitors (Users) who performed a certain action. That is, not the conversion rates displayed in the conversion rate reports above.

“Should I look at % of Sessions or % of Users?”

The short answer is, adapt to your site and conversion goals:

Conversion goals: Suggestions of factors to look at:
Lead Generation Users
Newsletter Signups Users
App downloads Users
Login Sessions
Signups for digital services Users
Usage of digital services Sessions
Ecommerce completed purchases Users
Ecommerce completed purchases and returning customers Sessions

Discussion time! Please leave a comment regarding your view on conversion rate and your site’s different goals.

Ask yourself “Is this something we want visitors to do every time they visit, or something we want as many visitors as possible to do?”

For example regarding an A/B test, a campaign, site changes etc. Another example: to make more visitors go through a funnel, it’s often more interesting to look at the % of Users who reach a certain stage. If you instead look at the % of Sessions, visitors that visited your site several times before converting will count multiple times, the first visits as drop offs and the last visits as conversions.

Other factors to consider when choosing the conversion rate for a specific goal:

  • Cross device: If a visitor came in to your site through multiple devices that were not connected, through for example UserID, s/he counts as several visitors. The cross device behaviour can affect conversion rate at Sessions and User levels in several different ways. A converting visitor with 2 mobile visits, 2 desktop visits will at the User level be counted as 1 out of 2 = 50% and at the Sessions level as 1 out of 4 = 25%. Start with what you know about your cross device behaviour, visitors who complete purchases etc at your site and choose what you think best mirrors what you want to optimize. None of the ways available are perfect. It’s mostly about making sure that the cross device function works correctly so that you can avoid having a high percentage of visits that can’t be connected to a User ID.
  • A/B testing tools such as Optimizely and VWO are usually based on User level. Therefore, it might be a good idea to check the GA User level data if you send data to GA from Optimizely. Of course, you can also look at Sessions level data if you think that it’s more relevant.

Notes regarding Ecommerce: Revenue per User
If you run an Ecommerce site, your main focus should be to look at Revenue per User (Revenue/Unique visitor) since it includes all changes regarding your conversion rate, average order value and transactions per user.

“Can’t I just look at Ecommerce conversion rate anyway? It’s a lot more simple, how much of a difference can there really be?”

Let’s look at an example.
User with three sessions

User converts in the third session

Multiple users with mulitple sessions

What will the conversion rate be now

Who only has three visitors to their site? You might be thinking “Lovely example, but it’s out of proportion. How big can this difference really be in real life?”

Good question!

Here are some differences in conversion rate between Sessions vs user level on three Swedish sites

Here’s how big the difference in conversion rate is depending on if you count on % of Users or % of Sessions:

Let’s look at real data from three Swedish sites:

How to calculate conversion

The question that you need to ask yourself now is:
a 9 – 85% error margin, is that the kind of precision that you feel comfortable with when evaluating your (tough) CRO work?

Well do ya, punk


How to calculate the % of visitors who converted

1. Go to the Audience > Overview Report

This is one of the few reports in which you can see both the number of Users and Sessions.

Audience overview

2. Create a segment for visits that contained a conversion which matches the goals you want to look at.

Pro tip: You can see how goals are configured and create a segment with the same configuration in Admin > View.

Create a segment that matches your goal: Page view
Goal Pageviews

Create a segment that matches your goal: Event
Goal events

Create a segment that matches your goal: E-commerce transaction
For Ecommerce businesses, there is a built in segment called “Sessions with Transactions”
ecommerce goal

3. Apply your own segment together with the built in segment “All Users” and calculate!

CR for Users



  • You can calculate your conversion rate as both % of Visitors (Sessions level) and as % of Visitors (User level)
  • Today, the conversion rate reports in GA use the Sessions level.
  • Which one you should choose depends on your conversion goal. “Is this something we want visitors to do every time they visit, or something we want as many visitors as possible to do?” For Ecommerce sites, look at Revenue per User
  • If you want to measure conversion rate at the User level, create segments and calculate the number of users in the Audience > Overview Report
  • The next time you set up an A/B test, a dashboard or a goal for re-design, think about which level you want to look at (Session or User).
  • To be continued…

Discussion/Questions: How do you calculate conversion rate at your company?

Read also

Conversionista is open for business in The Netherlands.
Conversionista is open for business in The Netherlands. Read more.