Magnetic, true, declination
- True north: toward the geographic North Pole. The top of a map, the north arrow on a plan, and sun position calculations all use it.
- Magnetic north: where a compass needle points. It is offset from the rotation axis and moves a little every year.
- Declination: the angle from true north to magnetic north. West of true north is negative, east is positive.
Declination by city (autumn 2026)
| City | Declination | Compass reading to map direction |
|---|---|---|
| New York | about -12.5° (west) | compass − 12.5° |
| Toronto | about -10.1° (west) | compass − 10° |
| London | about +1.2° (east) | compass + 1° |
| Los Angeles | about +11.3° (east) | compass + 11° |
| Sydney | about +12.8° (east) | compass + 13° |
| Seoul | about -9.0° (west) | compass − 9° |
How to convert
One formula: true bearing = magnetic bearing + declination. Going the other way, to find a map direction with a compass, subtract the declination.
| Place | Phone compass reads | Map direction (true) |
|---|---|---|
| New York (-12.5°) | 192.5° | 180° (due south) |
| Los Angeles (+11.3°) | 168.7° | 180° |
| London (+1.2°) | 178.8° | 180° |
When it matters
| Situation | Effect of a 10° error |
|---|---|
| Calling a window south or south-east | Near a boundary, the label changes |
| Lining up a sunrise behind a landmark | At 1 km, you miss by about 175 m |
| Aiming a satellite dish | The beam is narrow; you may get no signal |
| Following a map bearing on a trail | About 175 m off for every kilometre walked |
| Sorting photos or arranging furniture | Barely matters |
In Compass Camera
The bearing shown in the Android app "Compass Camera", and the bearing saved with each photo, is the raw sensor value: magnetic north. The Sun and Moon card converts sunrise and sunset bearings to the same magnetic basis using the declination your device calculates, so you can compare them directly with the compass on screen.
Read the compass number
The large number at the bottom (for example 186° S) is the magnetic bearing the camera is pointing at. To turn it into a map direction, add your declination. In New York the declination is about -12.5°, so 186° becomes about 174°.
Check your location and declination
From the location button on the Sun and Moon card, pick a city or enter coordinates, and the magnetic declination is shown alongside. On most Android devices it is filled in automatically; if not, you can type it in. Sun and Moon unlocks after one short ad.
FAQ
Which north does Google Maps use?
Map apps usually correct for declination using your location and show true north. If a map app and a compass app disagree by roughly your local declination, that is a difference in reference, not a broken sensor.
How fast does declination change?
Typically a fraction of a degree per year in most populated areas, so for everyday use the same value is fine for a few years. Use the current year’s value for precise work.
Compass Camera
No sign-up, no location permission, and your photos stay on your phone. Free on Android.