Compass Test
Check your phone's compass heading and how accurate it is.
Heading
—
Direction
—
Reference
absolute
Magnets throw a compass badly off. Move away from cases with magnetic clasps, car mounts, speakers and laptops before judging accuracy, and figure-eight the phone to recalibrate.
Your test runs locally in your browser. No device data is uploaded.
How to use the compass test
Hold the phone flat and level, allow motion access when the browser asks, then turn slowly on the spot. The heading should change smoothly through 360 degrees and settle on north when you face north. Compare it against a physical compass or a known direction, such as a street you can check on a map.
What is being measured
The magnetometer, which senses the Earth's magnetic field, usually combined with the gyroscope and accelerometer to work out which way the device is pointing. The test shows the heading in degrees, where 0 is north and 90 is east, and the nearest cardinal direction.
It also reports whether the browser is giving an absolute heading, referenced to true north, or a relative one referenced to wherever the device happened to be when the test started. A relative heading looks convincing but is not trustworthy for navigation.
Why compasses go wrong
Magnetic interference, almost always. Cases with magnetic clasps, magnetic car mounts, speakers, laptops and steel desks all distort the field enough to swing the reading well off. Move somewhere clear of metal before deciding the sensor is faulty.
If it is consistently off, recalibrate by moving the phone in a figure-eight a few times, which is what map applications ask for. A sensor that never settles, even away from interference and after calibration, is a genuine hardware fault.
Frequently asked questions
- My compass points the wrong way.
- Magnetic interference is the usual cause. Cases with magnetic clasps, car mounts, speakers and laptops all pull the reading off. Move away from metal and magnets, then recalibrate by moving the phone in a figure-eight a few times.
- What does a relative reference mean?
- It means the browser is reporting a heading relative to wherever the device happened to be when the test started, not to true north. iOS Safari and Android Chrome normally give an absolute heading; if you see relative, the direction shown is not trustworthy.
- Why does nothing happen on my computer?
- Desktops and most laptops have no magnetometer. This test needs the hardware in a phone or tablet, and it also requires a secure HTTPS connection and, on iOS, explicit motion permission.