Compass Test

How to test your phone's compass

1. Open this page on your phone and tap Start compass. On iPhone, tap Allow when Safari asks for motion and orientation access.
2. Hold the phone flat in front of you, screen up and away from metal, magnets, laptops and speakers. The red N on the dial points to magnetic north.
3. Turn slowly on the spot. The heading should rise smoothly from 0 to 359 degrees without jumps, and the steadiness box should stay within a couple of degrees when you stop.
4. Check it against a known direction: a street that runs north-south on a map, or the sun low in the east in the morning and the west in the evening.
5. If the accuracy or steadiness is poor, wave the phone in a figure 8 to calibrate it and check again. Type a bearing in Target bearing to turn until the arrow says On target.

What the results mean

The heading is the direction the top of the phone points, in degrees clockwise from north: 0 is north, 90 east, 180 south and 270 west. Here is how to read the boxes:

• Compass: Yes means the phone has a magnetometer and the browser gives a real north-referenced heading. No means there is no compass, or the browser only reports orientation relative to where the page started.
• Accuracy (iPhone only) is the phone's own estimate. Under ±15° is good; "Not calibrated" or more than ±30° means it needs a figure 8 calibration. Android browsers do not report accuracy, so use steadiness and a known direction instead.
• Steadiness is how much the reading wobbles over 3 seconds while you hold still. Within ±2° is steady; more points to interference from something magnetic nearby, or a phone being moved.
• Held flat warns when the phone is tilted more than 25°. The heading here assumes a flat phone, like holding a paper map.
• Magnetic field appears only in browsers that expose the raw magnetometer. Earth's field is 25 to 65 µT; much higher means a magnet or metal is close.

Magnetic north and true north

Phone compasses sense Earth's magnetic field, so this page shows magnetic north. True north, the direction of the North Pole on a map, differs by the magnetic declination, which is close to 0° in some places and more than 10° in others. Map apps correct for it using your location; this test does not, so a few degrees of difference from a map is expected. For your declination, search for a magnetic declination calculator from NOAA or the British Geological Survey.

Why phone compasses go wrong

The magnetometer is a tiny chip that measures magnetic fields in three directions. Anything magnetic near it bends the reading: magnetic phone cases and car mounts, a laptop, speakers, steel desks, rebar in concrete floors and car bodies. The phone learns the offsets of its own metal parts during calibration, which is why a figure 8 fixes most bad readings. After a new magnetic case or a repair, the old calibration no longer fits, so calibrate again. More in how to calibrate your phone compass.

Common problems and fixes

The compass points the wrong way

Take off magnetic cases and step away from metal and electronics. Wave the phone in a figure 8 for 10 seconds, rotating it in every direction. On Android, Google Maps also offers compass calibration from the blue dot. On iPhone, check Settings > Privacy & Security > Location Services > System Services > Compass Calibration is on.

The page says "Compass: No"

The phone may have no magnetometer: many budget Android phones and most tablets without GPS leave it out. It may also be the browser: use Chrome or Samsung Internet on Android and Safari on iPhone, and allow motion sensors in the site settings.

The heading jumps around

Something magnetic is close, or the phone is tilted. Hold it flat, away from your car dashboard, laptop or speaker, and test again outdoors. If it still jumps in open space after calibration, the sensor may be faulty.

Maps shows a wide blue beam

A wide beam means the phone is unsure of its heading. Calibrate with a figure 8 and the beam narrows. If location itself is off, try the GPS test next.