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Session Length as a User Engagement Metric
User Engagement

Session Length as a User Engagement Metric

You might have come across the term session length when reading about user engagement on the internet. If you are new in the mobile ecosystem and do not know what it is and what it can mean for your business, then the article has got you covered. Keep reading to learn more!

What Is Session Length?

One of the essential metrics for user engagement is the average session per user. The session length or the app session definition is the amount of time a user spends on your application in a single session. Now let’s divide the phrase and understand the meaning separately; the single time of user interaction is the “session,” whereas length stands for the duration of the session on your application.

As an example, let’s say you have an eCommerce application. So the time when your user opens your app, scrolls, surfs, and purchases till the user closes it refers to the duration of the length of the session.


Note that if the user comes back at a predetermined time, it will be counted in the initial length of the session. However, the meaning might vary for some apps as they include the streaming time in the background and the foreground.

Another related term is average mobile app session length, which is widespread among user metrics. So what is the average length of engagement? The average session duration definition, in simple words, would be a way to measure the concentration by calculating avg session duration using the average session duration formula. We’ll come to the details of the calculations in a minute.

Why Session Length Is Important for User Engagement?

For any business, users are the bread and butter. Nonetheless, by users, it means active users who frequently engage with the company, especially when it comes to this digital era where almost every business runs online and mobile. Out of multiple user engagement metrics, the engaged sessions per user is a crucial one on which user engagement relies.

The mobile app sessions analysis or the session length offers information about average session duration by industry, age, gender, etc., depending upon your business marketing goals. So when you know how, when, and for how long is the average engagement time per session, you can identify if the objectives of your application are being fulfilled or not. There is no other metric that would tell if your app can touch the average session duration benchmark.

Does Longer Session Duration Mean Higher Engagement?

Understanding the user expectation and behavior is critical in evaluating session length. Although mobile users, on average, spend around five minutes in an app, this number might vary from business category to category. Therefore, do not let the session length metric befool you by thinking that you are only doing better when your session length is longer. Hence, instead of focusing on the general average session length, it is more important to follow the category benchmarks and historical and seasonal trends.

If you are a product delivery app, you do not desire long sessions. In such cases, long session lengths might indicate some issues that your user might be having while using the app. Similarly, a game application’s session length has to be longer than other apps to see if it is engaging and interesting for the user.  

According to Statista’s report relying on the data by Adjust, vertical-based average session durations in 2019 and 2020 are observed to be as in the graphic below.


Once you know if your purpose is being served or not, you can easily track the user behavior and make the necessary reforms in your app to enhance the typical engagement length. Additionally, by knowing the average engagement time, you know you can get information on the quality of the experience your application offers to the users. Finally, you can understand the flow, analyze the progress and work for better user engagement.  

How to Calculate Session Length

To calculate the session length, you need to know two things exactly: the time the user launched your application and the time the user exited or closed your application. Usually, the length of average engagement is measured in minutes and seconds. However, remember that you can even customize the calculation as per your business goals and objectives for the application. To make tracking more accessible, you can use various analytics tools such as Flurry, Mixpanel, or Firebase, to give a few examples among many.

If you want to do the calculation by yourself, the simple formula is as shown below:

Session length = Timestamp when the user closes the app – Timestamp user joins or starts the app

For example, your user opened your food delivery app at 9:01 pm and closed your app at 9:15 pm, and then the session length of this particular session would be fourteen minutes.

9:15 – 9:01 = 14 minutes

The Calculation of Average Session Length

If you wish to find out the average number of sessions per user, then you can add all the session lengths in a given time frame and divide it by the number of sessions of the timeframe.

Continuing the same above, let’s say your user opens the same food delivery app in four app session intervals in a day for five minutes in the first session, three minutes in the second session, six minutes in the third session, and ten minutes in the fourth session. Now the average session length would be:

(5 + 3 + 6 + 10) / 4 = 6 minutes


Session Quality: Another Metric to Keep in Mind

Now that you know all about session length understand that it is not what your user engagement relies on. You must also take into consideration the quality of the session.

What Is Session Quality?

Another metric to track average engagement length per user has been introduced by Google Analytics: session quality. You can quickly know how close your user is to purchasing or availing your businesses’ service using the metric. Typically, you estimate how each session was about to turn into conversion by evaluating engaged sessions per user. You get results in the form of numbers that range from 1 to 100. If you receive a score closer to 100, your user was close to making the conversion. However, if the score is closer to 1, according to your mobile app sessions analytics, your user is far away from transacting.

When the results of both session length and session quality are combined, better results are generated, and high user engagement is observed. Therefore, do not focus wholly on session length. For you, the quality matters too, as it leads to a higher conversion rate.


Berkem Peker

Berkem is master of none, jack of all trades. Happens to be a Growth Strategist at Storyly. Knows/writes about growth frameworks and user behavior.

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