AirTag Geofence Alerts: Know When a Tag Arrives or Leaves a Site

What AirTag alerts does Find My offer?

For an AirTag you own, Find My offers two location notifications. Notify When Left Behind tells you when you walk or drive away without the tag. Notify When Found is for a tag that can't be located, and tells you once it is located again. Your iPhone also alerts you when the battery needs replacing.

You can also set Trusted Locations, such as home or the office. Leave the tag there and no separation alert is sent.

Both location alerts work well for keys and bags you carry. Both follow you or a lost item. Neither tells you that a tag reached or left a place.

Does Find My send an AirTag geofence alert?

No. Find My does have arrive and leave alerts, but only for friends who share their location. You can hear when a friend arrives at a place or leaves it. There is no such setting for an AirTag or any other item.

Notify When Left Behind is the closest, but it measures something else. It fires when your phone and the tag part ways. It does not tell you that the tag left a place.

Take a trailer that stays in a yard overnight and is towed out at 11 pm. The figure below shows what each alert does that night.

How an AirTag geofence alert works

An AirTag geofence alert compares each location report from a tag with a site you draw on a map. A report inside the site after one outside it is an arrival. A report outside the site after one inside it is a leave.

Those reports come from a crowdsourced network. Any phone that passes hears a tag and sends its location, encrypted, with the time it was seen. These networks are large (Apple counts over a billion iPhone, iPad and Mac devices, and Google over a billion Android devices).

You pick the alert for each site: arrival, leave, or both. The steps for drawing a site are in our guide to creating a geofence.

How long does a geofence alert take to arrive?

A geofence alert arrives with the first report from the other side of the site line. So the timing depends on when a phone next passes the tag.

On a staffed site or near a busy road, reports come in often. On a remote yard at night it can take longer. The alert arrives once someone walks past or the unit reaches a busier road.

Every report keeps the time it was seen. So the history shows when the tag was last seen inside the site and first seen outside it.

Where arrival and leave alerts help

Pick the alert by what should happen at each place.

• Leave alerts for places where equipment should stay put: the yard, a closed site, a locked store.
• Arrival alerts for places where equipment is expected: a job site, a customer, the repair shop.
• Both on the home yard, so you see each unit go out and come back.

A leave alert also works for an approved zone. Draw the approved area as the site. The first report from outside it sends the alert.

Speed matters after a theft. The NER's 2016 theft report counts 11,574 equipment thefts in the US and 2,442 recoveries. Delays in discovering a theft come first in its list of reasons for low recovery.

A leave alert shortens that delay. You learn of the move from the first report outside the yard, not on Monday morning. What to do next is in how to track a stolen AirTag.

What to expect from geofence alerts

• Building-level position. A report places the tag near the phone that saw it. That is enough to tell which site a unit is at. Draw each site a little wider than its fence line.
• Updates come from passing phones. Busy places report often. A remote corner reports when someone next walks past.
• Location, not engine data. A tag tells you where a unit is. It does not report hours, fuel or faults.
• Where, not who. An alert shows that a unit left. It does not show who moved it.

See the three tag sizes →