How does Find My iPhone (and similar apps) work?

A device-locating app is one of those features everyone knows exists, but hardly anyone really understands. Most people only use it once in a blue moon, usually in mild panic, holding someone else’s phone and expecting the map to point directly at the missing device. But that’s not how it works.

The problem is that the find-my-device types of apps never promised the level of precision people expect from it. It isn’t a real-time tracking system. Your phone isn’t broadcasting its location constantly, partly because that would murder the battery, and partly because it would be a privacy nightmare. Instead, the device records its location when it can, using whatever method is available at the time. What the app shows you is the last known location, not a live feed of where the phone is right now.

Most people assume GPS is doing all the heavy lifting. GPS works well outdoors, where the phone has a clear view of the sky. Inside buildings, blocks of flats, shopping centres, or basements, its accuracy drops sharply or disappears altogether. When that happens, the phone switches to other ways of estimating location.

One of those is the mobile network. Phones are always connected to nearby masts, which allows for a rough location estimate. Rough is the key word here. It can usually tell the area or neighbourhood. It cannot tell you where in a building the phone is. That approach makes sense when a device has gone missing somewhere in town. At home, it’s basically redundant.

Wi-Fi does far more work than people realise. Phones recognise nearby Wi-Fi networks and compare them against enormous location databases built by Apple and Google over time. That’s why location can work reasonably well indoors. The catch is that if your entire home uses the same Wi-Fi network, the system has no way of telling the difference between your kitchen and your bedroom. As far as it’s concerned, it’s all the same place.

There’s also Bluetooth and nearby devices. Modern systems can use other phones passing close to a lost device to anonymously report its location. It’s a clever setup and very effective in public spaces. Inside a home, it doesn’t change much. Everything is too close together and radio signals bounce around in ways that make precision impossible.

That’s why a device locator often shows a drifting pin or a location that feels vaguely wrong. A phone under the sofa can appear further away than one in the next room. A device upstairs might look closer than one downstairs. That isn’t the app being broken. It’s just how radio signals behave indoors.

Which brings us to the point most people miss. The find-my-device apps were designed to recover devices lost outside your home and to protect your data. That’s why the most useful feature in the entire system is playing a sound. The map gets you roughly close. Your ears do the rest.

Most of the myths around these apps come from unrealistic expectations. A switched-off phone isn’t being tracked because it isn’t transmitting anything. Location isn’t accurate to the centimetre because consumer technology simply doesn’t work that way. And phone theft has become far less profitable precisely because devices are tied to accounts and difficult to reuse.

Device locator apps aren’t miraculous, and they’re not pointless. They’re tools with very specific strengths and very clear limits. Once you understand what they’re really built to do, they stop being frustrating and start making sense.