What is Session Length?
The Session Length of an app is the amount of time from when a user launches the app until they stop using or leave the app. It tracks the duration of an individual, continuous experience in the app. Depending on the type of app, Session Length can be defined more narrowly as needed (e.g. a streaming app may timeout after a certain duration or track time running in the background).
Advice from Mobile App Experts
“It is important for app publishers to understand whether their app’s mission is best served by keeping users in the app as long as possible or by returning them as quickly as possible, and only session length can tell them that. Session length is not the only metric for measuring engagement, but it is one that really matters.” - Henry Cipolla, CTO of Localytics
How to calculate Session Length
Time user becomes inactive
time app was launched
(#) Session Length
The most basic calculation for Session Length is the time the app was launched subtracted from the time the user becomes inactive (or leaves the app). Of course this should be customized to fit your app type and objectives.
Tools like Mixpanel or Google Analytics make it easy to customize and track exactly what you determine to be Session Length for your app.
Session length is a critical mobile app metric because it provides the baseline for user engagement. Depending on the purpose of your app, you can determine if users are staying in the app long enough to complete desired actions (e.g. complete a purchase, connect with more people, share content, spend an increasing amount of time, achieve a new level, or unlock add-ons or special features).
For example, if you have a commerce app and the checkout process takes four minutes, you need to make sure people are staying in the app for at least four minutes or shorten the checkout process.
For some apps, increasing Session Length may not be the objective which means this metric is less helpful as a measure of engagement. An example of this might be a security app like Google Authenticator (only need it long enough to get the code) or 1Password or perhaps even a service app like Uber or Lyft where the longer someone is in the app the more likely they are to be frustrated (i.e. not able to request or secure a driver).
Understanding the objective your app and the expected user behavior is critical for effectively tracking and improving Session Length.
Relevant Mobile App Metrics and KPIs:
On average, mobile users will spend approximately five minutes in an app. Of course, this varies notably based on app type. Gaming, media and entertainment apps tend to engage users for longer while social networking and ecommerce apps fall on the shorter spectrum of Session Length.
It’s important to track Session Length against the objectives for your specific app. It’s helpful to compare your current Session Length with both industry benchmarks for your type of app and historical trends for your app (i.e. Session Length from last year/month compared to this year/month).