What is Dwell Time?

Definition

Dwell time is how long a visitor remains inside a venue, measured in WiFi analytics from when a device is first detected to when it stops being seen. It is used to distinguish passers-by from genuine visits, compare performance across days and zones, and time follow-up messages so they land at a useful moment.

What is being measured, and what is not

Dwell time is a proxy, not a fact. It measures device presence within radio range, which is not the same as a person being inside, seated, or spending money. A device on a pavement table, in a car in the car park, or belonging to a staff member all register. The usual corrections are a minimum threshold to exclude brief passes, an upper cut-off to exclude devices that never leave, and excluding known staff devices. State the thresholds you use, because a dwell figure without them is not comparable to anything.

Using it operationally

Dwell time is most useful as a relative measure. Compare Tuesday against Saturday, lunch against dinner, or one zone against another, and the trend is informative even if the absolute number is soft. Rising dwell with flat revenue can point at slow service. Falling dwell during a specific shift is worth investigating before it shows up in reviews. In marketing terms, dwell is what makes a post-visit message land correctly: a review request that fires after a genuine forty-minute visit reads as reasonable, while the same message after a two-minute pass through the door reads as spam.

The randomisation problem

Passive dwell measurement historically relied on the MAC address in probe requests staying constant. Modern phones randomise that address, which inflates unique-device counts and truncates measured sessions. Presence-based dwell figures from unauthenticated devices should therefore be treated as directional at best. Dwell measured across an authenticated portal session is far more reliable, because the session is tied to a login rather than to a hardware identifier the phone deliberately changes.