Compass

Hold your phone flat and this shows which way you are facing, as a three-digit bearing and as a named compass point. Enter your local declination and it converts magnetic north to true north. Lock a bearing and it tells you how far off course you have drifted.

How to use it

1. Tap to allow motion access. On iPhone this needs a deliberate tap each visit.
2. Hold the phone horizontal, screen upward. The mark at the top of the dial is the direction you are facing.
3. Enter your magnetic declination — positive for east, negative for west. Any local topographic map prints it in the margin.
4. To follow a bearing, point at your target and press Lock. The steering line then reads “turn 12° left” until you are back on course.
5. The back bearing is shown alongside, which is the direction to return the way you came.

Magnetic north is not where the map says north is

A compass needle does not point at the North Pole. It aligns with Earth’s magnetic field, and the magnetic pole is a separate place — currently in the Arctic Ocean, several hundred miles from the geographic pole, and moving at roughly 30 miles a year.

The angle between the two, seen from wherever you are standing, is called declination (or magnetic variation on nautical charts). It is not a fixed correction. It depends entirely on your position on the globe, because it is a matter of parallax between two poles that are in different places.

The practical range is large. In Seattle, declination is currently around 15 degrees east. In Maine it is about 15 degrees west. Along a line running roughly through the US Midwest — the agonic line — it passes through zero, and a compass genuinely points at true north. In parts of Alaska it exceeds 20 degrees.

Here is why that matters in the field. Walk one mile on a bearing that is wrong by 13 degrees and you finish about 1,200 feet from where you intended — nearly a quarter of a mile. Over five miles you are more than a mile out. For finding a road that is fine. For finding a trail junction, a bothy, or a car park in fog, it is a serious error, and it is entirely avoidable by entering one number.

Every topographic map prints its declination, and it prints the date it was measured, because the value drifts. A map from 1995 will be a degree or two out today. If you have no map, the NOAA magnetic declination calculator gives a current figure for any coordinates.

The other correction the tool cannot make for you is local interference. A magnetometer measures the total magnetic field at its location, and it has no way to separate Earth’s field from anything else. A car body, a speaker magnet, a laptop hinge, a steel desk, an MagSafe case, or a pair of headphones will all bend the reading, sometimes by tens of degrees, and the tool will report the wrong answer with complete confidence. This page watches for the tell-tale symptom — a bearing that swings while the phone is still — and warns you, but the fix is physical: step away from metal and electronics.

What it does not do

It cannot correct for declination automatically, because that needs your location and a magnetic model, and this site makes no network requests and asks for no location permission. It has no idea of your altitude or your speed. Some Android browsers expose only relative orientation, in which case the tool says so rather than presenting a meaningless bearing as fact. And it is not a marine or aviation instrument — deviation from a vessel’s own steel is a separate correction that no phone can compute.

Nothing is uploaded. Bearings never leave your device.

Sixteen-point compass bearings

Point	Bearing	Point	Bearing
N	000°	S	180°
NNE	022.5°	SSW	202.5°
NE	045°	SW	225°
ENE	067.5°	WSW	247.5°
E	090°	W	270°
ESE	112.5°	WNW	292.5°
SE	135°	NW	315°
SSE	157.5°	NNW	337.5°

Approximate declination, 2026

Location	Declination
Seattle	15° E
Los Angeles	11° E
Denver	8° E
Chicago	3° W
New York	13° W
Miami	7° W
London	1° W
Sydney	12° E