What a Session Is in Web Analytics

What is a session in web analytics?

In web analytics, a session is one continuous group of a visitor's interactions on a site, opened by the first event and closed by inactivity, a new day boundary, or in some tools a change of campaign source. Analytics tools use the session as the container that holds pageviews, clicks, scrolls and conversions for a single sitting. Every product writes its own closing rules, so the number you read depends on which product produced it.

Does a session mean the same thing as a login session?

No. In authentication, a session is the server-side or cookie-backed state that keeps a person signed in until they log out or the token expires, which is a separate mechanism from the analytics unit described here. Everything below uses the analytics meaning.

When does a session start and end?

A session starts on the first tracked event from a visitor who has no session currently open, and ends when one of the tool's closing rules fires. Three closing rules are in common use: an inactivity timer that resets on every event, a calendar day boundary in the site's configured timezone, and a change in the campaign parameters attached to the URL. Before comparing your numbers with anyone else's, find those three rules in your own tool's reference and write down which ones it applies, starting with the inactivity timer.

How does GA4 close a session?

Google Analytics 4 closes a session after 30 minutes of visitor inactivity by default. Google's About Analytics sessions reference states that "a session ends or times out after 30 minutes of user inactivity", and the timer can be raised in the interface to a maximum of 7 hours and 55 minutes. That page lists inactivity as the closing condition and describes no midnight cutoff, which is one of the breaks from Universal Analytics, where a session expired at midnight in the view's timezone.

Campaign handling changed in the same migration. Google's Universal Analytics to GA4 comparison puts it directly: "In Universal Analytics, a new campaign will start a new session regardless of activity. In Google Analytics 4, a new campaign does not begin a new session." A visitor who arrives from an ad, then clicks a newsletter link 10 minutes later, produced two sessions in Universal Analytics and produces one in GA4. All three Google rules above were checked in September 2026.

How do other analytics tools close a session?

Every major tool starts from a 30-minute inactivity timer and then adds its own extra conditions on top.

Tool	Inactivity timeout	New calendar day	New campaign source	Other limits
Google Analytics 4	30 minutes, adjustable to 7h55m	not documented as a closing rule	does not open a new session	none documented
Universal Analytics (retired)	30 minutes	closes at midnight, view timezone	opens a new session	none documented
Adobe Analytics	30 minutes	not documented as a closing rule	not documented as a closing rule	12 hours of unbroken activity, 2,500 hits, or 100 hits in the first 100 seconds
Matomo	30 minutes, set by visit_standard_length	opens a new visit after midnight, site timezone	new campaign parameters or ad click IDs open a new visit	none documented
Plausible	30 minutes	not documented as a closing rule	not documented as a closing rule	none documented

The Adobe limits come from its Visits metric reference, which says "if more than 30 minutes lapse between hits, a new visit begins" and adds the 12-hour, 2,500-hit and 100-hits-in-100-seconds caps. The Matomo rules come from its visit definition FAQ, where the 30-minute default is set by visit_standard_length in seconds. Plausible's metrics definitions state that "a visit starts when a visitor first lands on your page and ends when no action is taken for 30 minutes". Where a cell says not documented, the vendor's own reference lists no such rule, which is weaker evidence than a stated guarantee.

Why does the same traffic produce different session numbers?

Different closing rules split the same event stream at different points. Take one visitor with six events in a single evening, in the site's timezone:

Time	Event	Gap since last event
21:40	lands from an organic search result	first event
22:05	views a second page	25 min
22:15	clicks a newsletter link carrying utm_campaign=autumn-digest	10 min
22:35	views a fourth page	20 min
23:50	views a fifth page	75 min
00:10	views a sixth page	20 min

A tool that closes only on inactivity breaks once, at 23:50, and reports two sessions. Matomo breaks three times, at 22:15 for the campaign change, at 23:50 for the timeout, and at 00:10 for the day boundary, and reports four visits. One visitor, six events, a 2x difference in the headline number, and no difference in the traffic. The same split explains why one person on a phone and then a laptop registers as two sessions and two visitors, which is what stitching a visitor's sessions together sets out to correct.

Where Matomo splits one evening into four visits

21:40 organic landing opens visit 1

22:15 campaign link opens visit 2

23:50 inactivity timeout opens visit 3

00:10 midnight opens visit 4

Is a session count a people count?

A session count is a count of sittings, not of people. One visitor who returns on Monday, Wednesday and Friday adds three sessions and one visitor, so sessions always run ahead of visitors on any site with returning traffic:

sessions per visitor = sessions / visitors

For a site reporting 12,400 sessions and 5,200 visitors in a month, that ratio is 12,400 / 5,200 = 2.38 sessions per visitor. Read the ratio as return frequency, and never report a session figure with a label like "people reached" or "users" attached to it.

Which metrics divide by sessions?

Bounce rate, pages per session, average session duration and the standard session-based conversion rate all use the session count as their denominator, which makes the boundary rules above a direct input to each one. Work the conversion rate as an example:

conversion rate = conversions / sessions

With 310 conversions and 12,400 sessions, the rate is 310 / 12,400 = 0.025, or 2.5 percent. Move the same traffic and the same 310 conversions into a tool that splits on campaign changes and midnight and reports 18,600 sessions, and the rate reads 310 / 18,600 = 0.0167, or 1.67 percent. Nothing about the site changed. Pin one tool as the system of record for every rate metric, and note the denominator next to the number in any report that leaves your team.

Flowsery records every user session and its built-in analytics reports real-time traffic, funnels, goals and user journeys with no data sampling, so the counts cover the full event stream instead of an extrapolation from a subset. Sessions carry the pageviews and events that make each rate metric meaningful, so a session boundary that moves takes every downstream percentage with it.

Frequently asked questions

How long is a session before it times out?

Thirty minutes of inactivity is the default in Google Analytics 4, Adobe Analytics, Matomo and Plausible. The timer resets on every tracked event, so a visitor reading one page for two hours without scrolling or clicking still times out at the 30-minute mark from their last event. GA4 allows the timer to be raised to 7 hours and 55 minutes.

Does a session end at midnight?

That depends on the tool. Universal Analytics closed every session at midnight in the view's timezone, and Matomo opens a new visit when a visitor continues browsing past midnight in the site's timezone. Google's GA4 session reference describes inactivity as the closing condition and lists no midnight cutoff.

Does clicking a new ad start a new session?

In Google Analytics 4, no. Google's migration documentation states that a new campaign does not begin a new session in GA4, reversing the Universal Analytics behavior where a campaign change closed the open session and opened a fresh one. Matomo does open a new visit when a visitor arrives with new campaign parameters or ad click IDs.

Why does my tool report more sessions than visitors?

One visitor produces a new session on every return trip, so any site with repeat traffic reports more sessions than visitors. Dividing sessions by visitors gives return frequency: 12,400 sessions across 5,200 visitors is 2.38 sessions per visitor. A ratio close to 1.0 means almost nobody is coming back.

Can I change the session timeout?

Google Analytics 4 exposes the timeout in the interface up to a ceiling of 7 hours and 55 minutes. Matomo On-Premise sets it through visit_standard_length in the config file, in seconds. Changing the timeout changes every session-based metric on the site and breaks comparability with your own historical data, so move the value once and record the date you moved it.

Is a session the same as a session replay?

No. A session is the counted unit in your analytics reports, while a session replay is the reconstructed recording of what happened inside one of those sittings. The two share a boundary definition in tools that record and count in the same system, which is what lets a replay be opened directly from the session row that flagged a problem.

What actually gets counted inside one session?

A session is the container analytics tools use to hold everything a visitor does in one sitting: pageviews, clicks, scrolls and conversions. It opens on the first tracked event and stays open until a closing rule fires, so every action logged before that point belongs to the same session. Two visitors who each view three pages and click once produce sessions with the same contents, even when the tools disagree on where the boundary falls.

What limits does Adobe Analytics add on top of the 30-minute timeout?

Adobe closes a visit after 30 minutes of inactivity like the other major tools, then adds three more caps: 12 hours of unbroken activity, 2,500 hits, or 100 hits within the first 100 seconds. Whichever limit hits first closes the session, so a visitor who stays engaged past the inactivity window can still get cut off by the hit count. Adobe's own Visits metric reference lists these caps, and no other tool in the comparison documents anything like them.

How does Plausible define when a session starts and ends?

Plausible's metrics definitions state that a visit starts when a visitor first lands on a page and ends when no action is taken for 30 minutes, the same inactivity window every other major tool defaults to. Plausible documents no midnight cutoff and no campaign-change rule, so an evening of browsing with a mid-visit ad click stays inside one Plausible session unless the visitor goes quiet for half an hour.

What's the difference between a session and a pageview?

A pageview is one loaded page. A session is the container that holds every pageview and event a visitor generates before a closing rule fires, and metrics like pages per session divide one by the other. A session boundary that shifts changes both numbers at once, since sessions carry the pageviews that make the ratio meaningful.