How accurate is Find My iPhone?

Find My can be accurate down to 20-25 feet of the iPhone location if all of the conditions are perfect, but perfection rarely exists in this world.

On a recent test, Find My displayed what end of the house the phone was located in, but the house had only one story. If the house or building has two or more levels, Find My cannot indicate what floor the phone might be on.

Find My can be wrong if the phone has changed location and has lost its connection to the Internet. In that case, Find My will display a "Last Known Location" for a day or so. After that, Find My will display a notice of "Offline".