Online Users
BeginnerOnline users is the number of distinct visitors who recorded at least one event within the last few minutes, measured over a rolling window.
Nothing is held open to count people: the figure counts identifiers seen inside a moving time window, so a reader who spends fifteen minutes on one long article without firing anything drops out of a five-minute window and reappears with the next signal. The window length is part of the number, which is why one site shows two different figures in two tools; the GA4 realtime report is built on the last 30 minutes, while some tools default to five. That also separates this metric from concurrent users in the infrastructure sense, where the count is open connections on a server rather than recent activity. The figure is a snapshot: it cannot be summed and it does not build up into daily traffic.
How it is calculated
Online users = number of distinct identifiers with at least one event inside the last few minutes
The identifier is the visitor identifier, so one person on two devices counts twice. The unit is people, and the window length belongs to the metric definition rather than being a filter applied afterwards; widening it from five to thirty minutes raises the number with no change in traffic.
FAQ
Sources:GA4 — Realtime report