How does a compass work on a smartphone?

This is a really good feature of a smartphone that not too many people know about.

I was asked to make a video on this, but I figured it would also be good to put together an article about it, as this is good information to know.

Ordinarily, the way a plain magnetic compass works is by use of a magnet that allows something to move. If it's a traditional handheld compass, the arrow can be moved by the magnet to tell you which direction you're facing. If the compass is made for marine or car use, there is a ball floating in liquid, and the magnet can move that to indicate direction.

Smartphones have no moving parts, so the way its internal compass works is different.

All modern smartphones have a magnetometer in them. But since that doesn't move, it is assisted by the accelerometer sensors in order to tell you which cardinal direction (as in north, south, east or west) you're facing.

You can turn off location (GPS), data and Wi-Fi and the compass feature of a smartphone will work since it requires no radio signals to function. All you need is a compass app. For Android, the app I prefer is GPS Test Plus, available in the Google Play Store. Apple iPhone does not have that specific app, but a search for "compass" in the app store will get you a compass app that more or less does the same thing.

There are a few very good reasons why it is important to know about the smartphone compass.

It's not just for navigating while in the woods...

When you hear the word compass, you may think of people using a compass outdoors such as for hiking, cycling, or any place where there are not roads marked by signs.

While true a compass comes in very useful for outdoor activities, it also comes in very handy in places like cities, large shopping malls and large parking lots.

The compass is your "backup navigation" for when the radio signals on the phone get blocked for whatever reason.

Is your compass calibrated?

Given the orientation of a phone changes quite a bit just from normal use, you may need to calibrate your compass periodically. This can be done through Google Maps. Launch the app, touch the dot showing your location, choose to calibrate the compass, and then twist your phone in a figure-8 motion to calibrate. The app does show a graphic with instructions.

Having location (GPS) enabled is required to calibrate the compass in Google Maps. Having data enabled is not required. The map will probably show up as blank when you load Google Maps this way, but you can access the compass calibration so the compass works properly.

A simple example of using only a compass

A large shopping mall parking lot is one of the easiest examples.

After parking your car, take out your phone and launch the compass app. Face away from the building you need to enter. Now you know the direction you need to go when exiting the building to get back to your car. Remember this. When you exit the building later on, go that direction and you will be led in the direction of where your car is.

As "connected" as we like to think we are, we're really not

Smartphone navigation is great - when it works. When it fails, it likes to do so in spectacular fashion.

It is nothing short of amazing that even when a phone can determine location by cell tower, Wi-Fi and GPS all at once that it still manages to "get lost", leaving you lost when you need navigation working the most. And the navigation doesn't break just a little bit. When a phone doesn't know where it is, it really doesn't know where it is.

Using the phone's compass does not rely on towers, satellites or data. As long as you're not in a metal box (like an elevator), it will work.

Does a compass give you perfect cardinal direction? No, and it never has. But it's good enough to at least point you mostly where you need to be.

It's better that nothing, and if you need it, it's there.

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Published 2020 Nov 17