How sessions are counted
A session begins each time a user opens your app or website from a fully closed state, or reopens it after being in the background for at least 30 seconds. Returning within 30 seconds continues the current session instead of starting a new one. Session data aggregates across a user’s devices. Activity on any of a user’s Subscriptions updates their session data, so a user with both a mobile app and a website is treated as active when they use either one. Email and SMS Subscriptions reflect the session values from the user’s most recently active push Subscription. OneSignal also tracks Usage Duration, the total time a Subscription was active on your app or site. Usage Duration is only tracked when a session exceeds 60 seconds.Session properties
Each Subscription carries three session properties:
Session data aggregates across a user’s subscriptions. Activity on any of a user’s devices updates their last session, and email and SMS subscriptions reflect the values from the most recently active push subscription. See Users and Subscriptions for how these properties behave across a user’s devices.
Sessions in segmentation
You can build Segments using session properties without any custom code:- First session and Last session filters target users by when they first became active or how long they have been inactive (for example,
Last Session > 7 days agofor a re-engagement audience). - Session count filters target users by how many times they have opened your app or site.
Sessions in analytics
App Sessions is a default conversion metric: it counts every qualifying app open as a session, and sessions are attributed to a message when one qualifies. Sessions also appear on push message reports and in Template Analytics as a per-message metric. Sessions recorded before June 25, 2025 appear on the outcomes chart and follow the legacy outcomes attribution model rather than the conversion metrics attribution model. See Conversion metrics for how sessions are attributed today.Sessions and in-app messages
In-app messages are evaluated at the start of a session. A user must match the message’s audience before a new session starts for the message to display, which is why a user who joins the audience mid-session sees the message on their next app open rather than immediately. See How in-app messages are shown for the full requirements.Sessions and billing
A mobile Subscription’s last session determines whether it counts toward Monthly Active Users (MAU) for billing. See Billing FAQ for how MAU is calculated.FAQ
Why don’t sessions match other analytics tools?
A session begins each time a user opens your app or website from a fully closed state, or reopens it after being in the background for at least 30 seconds. Returning within 30 seconds continues the current session instead of starting a new one. Other analytics tools may define a session differently. For example, some might count any app open that lasts at least a couple of seconds as a separate session, which produces higher session counts than OneSignal.How are sessions counted across a user’s devices?
Session data is tracked per Subscription and aggregated at the user level. Activity on any device updates the user’s last session, and email and SMS Subscriptions inherit session values from the user’s most recently active push Subscription. Assign External IDs to unify a user’s Subscriptions so their session data is combined.Related pages
Users and Subscriptions
How Subscriptions store session properties and behave across a user’s devices.
Segmentation
Build audiences using First session, Last session, and Session count filters.
Conversion metrics
Track App Sessions and other conversions with cross-channel attribution.
In-app messages
Why in-app messages display on a new session.