Bearing calculator
Pick two places and see which way to go: the bearing of the shortest route and of the constant-bearing route, both from true north and on your compass, with the local magnetic declination for any date you choose.
Declination shifts a little every year. The model covers 2025 to 2029.
Example From New York to London. Search for your own places or tap the map.
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Result
Bearing at the start of the shortest route
51.2°Northeast (NE)
True bearing: measured clockwise from true north.
- On a compass (magnetic)
- 63.7°ENE
- Bearing on arrival
- 108.3°ESE
- Distance
- 3,470 mi
On the shortest route the bearing keeps changing: it turns 57° between start and finish.
Constant bearing (rhumb line)
78.0°East-northeast (ENE) · the same all the way
- On a compass (magnetic)
- 90.5°E
- Distance
- 3,609 mi
- Longer than the shortest route
- 139 mi4.0%
It’s easier to follow (you never change course), but it takes a detour. On a Mercator map it’s a straight line.
Compass rose
Magnetic declination (WMM2025)
| Place | Declination | Change per year | Horizontal field |
|---|---|---|---|
| A · New York | 12.48° W | 0.04° E/yr | 21,061 nT |
| B · London | 1.22° E | 0.17° E/yr | 19,553 nT |
With a compass: subtract an east declination from the true bearing, or add a west one. Here it’s 12.5° W.
Save or share this bearing
How to use it
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Choose two places
Search for a town or an address, paste coordinates, use your location or tap the map. You can drag A and B around.
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Read both bearings
The shortest route changes bearing along the way, so you get the starting and the arrival bearing. The rhumb line has just one.
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Set it on your compass
Next to it you get the magnetic bearing, already corrected for the declination at A on the date you picked, plus a compass rose.
What it’s for
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Map and compass navigation
To head cross-country to a summit or a hut, the magnetic bearing is the one you set on the compass.
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Sailing
A rhumb line is the constant-course track drawn on Mercator nautical charts: you can follow it without changing course.
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Aiming an antenna
To point an antenna at a distant tower you need the great-circle bearing, not the rhumb line.
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Understanding the globe
See why the shortest route from New York to London sets off to the northeast and arrives heading east-southeast.
How it’s calculated
A bearing is the angle from north to the direction of travel, measured clockwise: 0° is north, 90° east, 180° south and 270° west. Mapsfera gives you three of them.
The great-circle bearing is computed on the WGS84 ellipsoid with GeographicLib: it’s the inverse geodesic problem, which returns the distance and the start and end bearings. The rhumb line uses the isometric latitude, the same quantity that stretches the Mercator map, which is why a rhumb line is straight on it. The magnetic bearing is the true bearing minus the declination from the World Magnetic Model WMM2025.
Rhumb line (constant bearing)
bearing = atan2(Δλ, Δψ) distance = Δμ · √(Δψ² + Δλ²) / Δψ
λ is longitude, ψ the isometric latitude and μ the meridian arc from the equator. When Δψ is 0 (due east or west), the radius of the parallel is used instead.
Magnetic bearing
magnetic = true − declination
Declination is positive east and negative west. With 13° W, a true bearing of 90° reads 103° on the compass.
| New York | 40.66270° N, 73.93870° W |
|---|---|
| London | 51.50740° N, 0.12780° W |
| Starting bearing on the shortest route | 51.2° (Northeast) |
| Arrival bearing on the shortest route | 108.3° (East-southeast) |
| Shortest distance | 3,470 mi (5,584 km) |
| Constant bearing (rhumb line) | 78.0° (East-northeast) |
| Rhumb-line distance | 3,609 mi (5,808 km): 139 mi (224 km) more (4.0%) |
| Magnetic declination in New York | 12.48° W |
| Starting bearing on the compass | 63.7° |
The shortest route leaves New York heading northeast and reaches London on a bearing of 108.3°: great circles bulge toward the pole, so the course swings round on the way. The rhumb line holds a single bearing of 78.0° but covers 139 mi (224 km) more.
True north vs magnetic north
True north is set by the Earth’s axis; a compass needle follows the magnetic field, which isn’t lined up with the axis and drifts from year to year. The angle between them is the magnetic declination. Mapsfera computes it with the World Magnetic Model WMM2025, the standard model of the US and UK militaries, NATO and the International Hydrographic Organization, published by NOAA and the British Geological Survey and valid from 2025 to 2029.
Across the US the declination swings from east to west: on October 31, 2026 it was 12.5° W in New York, 14.9° E in Seattle, 4.1° W in Chicago, and 7.4° E in Denver. It also moves every year (0.04° E a year in New York).
The model only covers the field from the Earth’s core, not local magnetic rocks or solar storms, so its typical error is 0.36° in 2025 and 0.40° in 2030. Near the magnetic poles, where the horizontal field is very weak, compasses stop working. The model marks a blackout zone there (under 2,000 nT) and a caution zone around it (under 6,000 nT), and the tool warns you if A or B falls inside one.
The 16 points of the compass rose
A compass rose splits the circle into 16 points of 22.5° each: North (N, 0°), North-northeast (NNE, 22.5°), Northeast (NE, 45°), East-northeast (ENE, 67.5°), East (E, 90°), East-southeast (ESE, 112.5°), Southeast (SE, 135°), South-southeast (SSE, 157.5°), South (S, 180°), South-southwest (SSW, 202.5°), Southwest (SW, 225°), West-southwest (WSW, 247.5°), West (W, 270°), West-northwest (WNW, 292.5°), Northwest (NW, 315°), North-northwest (NNW, 337.5°). The tool gives you the nearest one for each bearing; northeast, for example, runs from 33.75° to 56.25°.
Frequently asked questions
What’s the difference between a great-circle bearing and a rhumb line?
The shortest route between two points on Earth is an arc of a great circle, and its bearing changes along the way. A rhumb line keeps the same bearing the whole time: easier to follow with a compass, but longer. Over a few miles the two are practically the same.
How do I convert a true bearing to a compass bearing?
Use the magnetic bearing the tool gives you. To do it yourself, subtract an east declination from the true bearing, or add a west one. In New York or Seattle the declination is over 10°, so skipping this step can put you well off course.
Why does the declination depend on the date?
Because the Earth’s magnetic field, generated by liquid iron in the outer core, slowly drifts. WMM2025 includes the yearly change and is replaced every five years; the next model is due in late 2029.
What is the blackout zone?
It’s the area around each magnetic pole where the horizontal field is weaker than 2,000 nanotesla. A compass needle barely has the force to line up there, and the declination can be completely wrong. Around it there’s a caution zone, under 6,000 nanotesla.
How accurate is it?
True bearings are exact on the WGS84 ellipsoid. The declination has a typical global error of 0.36° in 2025 and 0.40° in 2030, more near the poles and where the rocks are magnetic. The model code reproduces the official WMM2025 test values.
Related tools
All toolsSources
- World Magnetic Model WMM2025: coefficients and test values · NOAA NCEI and British Geological Survey (public domain)
- The US/UK World Magnetic Model for 2025-2030: Technical Report (Chulliat et al., 2025) · NOAA NCEI, doi:10.25923/prbc-s316
- GeographicLib (distances and bearings on the WGS84 ellipsoid) · Charles F. F. Karney (MIT license)
- Place search and place names · Photon (Komoot), with OpenStreetMap data
- Base map · OpenFreeMap, with data © OpenStreetMap contributors