How does location sharing work?
Location sharing lets people you choose see where your phone is, live, on a map. Your phone finds its own position, sends it through the app you share with, and the app shows it only to the people in your list. That is the whole trick. The details below explain what happens along the way, and what it costs you in data, battery and privacy.
How your phone knows where it is
A phone uses three sources and blends them, because each one is good at something different:
- GPS satellites. Precise to a few meters under open sky, weaker indoors and between tall buildings.
- Wi-Fi networks nearby. The phone recognizes the networks around it and matches them to known places. This is what keeps the dot accurate inside a school or a mall.
- Cell towers. Rough, often a few hundred meters, but it works almost everywhere there is signal.
The phone mixes these into one best guess and shows it as a dot with a circle around it. A small circle means the phone is confident. A big one means it is guessing, usually indoors or underground.
Where the dot travels
- The app on your phone reads your position from the phone's location service. It can only do this if you allowed it in the phone's settings.
- It sends the coordinates over mobile data or Wi-Fi to the app's server.
- The server checks who you share with and passes your position only to them.
- Their app draws your dot on a map, with the time of the last update.
Most apps update often while you move and slow down when you sit still. That is why a friend on a bus seems to glide across the map, while someone at home may show "updated 20 minutes ago". Nothing is wrong. The phone is just saving its battery.
The three kinds of sharing
- One-off. "Here's my live location for the next hour, I'm on my way."
- Ongoing. Your family sees your location all the time, and you see theirs.
- Place-based. A notice when someone arrives at or leaves a place you marked, like school or home. This is called geofencing; we explain it in what geofencing is.
Data, battery and signal
Data. A location update is a handful of numbers, much smaller than a single photo. The map images on the other person's screen use more data than your updates. For most people location sharing is a rounding error on the phone bill.
Battery. Checking position in the background does cost battery. Good apps use the phone's motion sensors to notice when you stopped moving and check less often. The biggest drains are weak signal and constant navigation, not the sharing itself.
No signal. On the subway, in a basement or on a plane, the phone can't send anything. Others see the last known spot until the phone is back online, then the dot jumps to where you are now.
Where to share your location
Apple Find My is built into every iPhone. Open Find My, go to the People tab and choose "Share My Location". Free.
Google Maps works on iPhone and Android. Tap your profile picture, then "Location sharing", pick a person and how long. Free.
Family apps such as Protego, Life360 and Find My Kids build an ongoing family circle on top of this, with places, arrival notices and everyone on one map.
Privacy: the question that actually matters
The technology is simple and fairly harmless. The business model is where it can go wrong. Some apps that offer free sharing have earned money by selling aggregated location data to third-party brokers. That kind of data has been re-identified to individuals, sold for foot-traffic analysis and bought by government agencies.
Before you turn sharing on, search "[app name] sells location data" and read the current privacy policy. Apple Find My does not sell location. Protego does not either, ever. Life360 was criticized for it in the past and has since changed its policies.
Your phone also keeps its own list. On iPhone it lives under Settings, Privacy and Security, Location Services. On Android, under Settings, Location, App permissions. Every app that can see your location is on that list. If you're a teenager wondering whether your parents can track your phone, we've written that up too.
Location sharing in Protego
We built Protego for families who want sharing to feel like a small bit of magic rather than a watchtower. Everyone shows up on a parchment map with an avatar they picked, and the circle works both ways, so kids see their parents too. Plenty of teenagers end up checking on us more than we check on them. It runs on iPhone and Android, it is free for a circle of two, and a paid plan brings in the rest of the family.
Questions people ask
How does location sharing work?
Your phone works out where it is using GPS satellites, nearby Wi-Fi networks and cell towers. The app you share through sends those coordinates over the internet to its server, and the server passes them only to the people you chose. Their app draws your position on a map. Most apps update more often while you are moving and less often while you sit still, to save battery.
Does sharing your location use data?
Very little. A single location update is a tiny packet of numbers, far smaller than one photo. Loading the map pictures on the screen of the person watching uses more data than your updates do. Location sharing works on mobile data and on Wi-Fi.
Does location sharing drain the battery?
Some, because the phone has to check its position in the background. Well-built apps lean on the phone's motion sensors and check less often when nothing is changing, so the cost on a normal day is usually modest. A weak signal, like a long subway ride or a basement, makes the phone work harder.
Can someone see my location without me knowing?
Not through the normal sharing features. Apple Find My, Google Maps and family apps all require you to turn sharing on, and they show whom you share with. If you are unsure, open each app's sharing list and your phone's location settings, which list every app allowed to use your location.
Is location sharing safe?
Sharing with people you trust is safe in itself. The real question is what the app does with your data. Some companies have sold aggregated location data to brokers, others do not. Read the privacy policy before you turn it on. Protego never sells location data.
Is location sharing free?
The built-in options are free: Apple Find My and Google Maps location sharing cost nothing. Dedicated family apps usually have a free tier. Protego is free for a circle of two people, with a paid plan for a bigger family.