Compass Bearing Converter Formula

Understand the math behind the compass bearing converter. Each variable explained with a worked example.

Use the Compass Bearing Converter

Formulas Used

Cardinal Direction

main_direction = value < 22.5 ? 1 : (value < 67.5 ? 2 : (value < 112.5 ? 3 : (value < 157.5 ? 4 : (value < 202.5 ? 5 : (value < 247.5 ? 6 : (value < 292.5 ? 7 : (value < 337.5 ? 8 : 1)))))))

Radians

radians = value * pi / 180

NATO Mils

mil_nato = value * 17.7778

Variables

VariableDescriptionDefault
valueBearing (degrees from North)(°)135

How It Works

Compass Bearings

Cardinal Directions and Degrees

BearingDirection 0° (360°)North (N) 45°Northeast (NE) 90°East (E) 135°Southeast (SE) 180°South (S) 225°Southwest (SW) 270°West (W) 315°Northwest (NW)

Bearings are measured clockwise from true North. Output values: 1=N, 2=NE, 3=E, 4=SE, 5=S, 6=SW, 7=W, 8=NW.

Worked Example

Convert 135° bearing.

value = 135
  1. 01135° falls between 112.5° and 157.5°
  2. 02Direction: Southeast (SE)
  3. 03NATO mils = 135 x 17.78 = 2,400 mils

Frequently Asked Questions

What is a compass bearing?

A bearing is an angle measured clockwise from true north. 0° is due north, 90° is due east, 180° is due south, 270° is due west.

What is the difference between true and magnetic north?

True north points to the geographic North Pole. Magnetic north is where a compass needle points and varies by location (magnetic declination). The difference can be significant for precise navigation.

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Open Compass Bearing Converter