Calculate a reverse or back bearing from decimal degrees, DMS, or quadrant notation, with reciprocal azimuth, compass direction, and converted formats.

Use the same north reference for both directions. This is a local or planar reciprocal, not a geodesic return course.

0° to less than360°.

Reverse Bearing Formula

This calculator finds the opposite direction of a planar or compass bearing measured clockwise from the same north reference: 0° is north, 90° east, 180° south and 270° west. It keeps the result from 0° to less than 360°.

For 0° ≤ CB < 180°, use RB = CB + 180°. For 180° ≤ CB < 360°, use RB = CB − 180°.

  • Where RB is the Reverse Bearing (degrees)
  • CB is the current bearing (degrees) 

In other words, add 180° to the current bearing and wrap the result into 0° to <360° (equivalently: RB = (CB + 180) mod 360). In quadrant notation, keep the angle and swap both direction letters: N/S and E/W.

How to Calculate Reverse Bearing?

The following example problems outline how to calculate Reverse Bearing.

Use decimal degrees or degrees, minutes and seconds (DMS). In the three DMS fields, degrees and minutes must be whole numbers; minutes and seconds must be less than 60. A quadrant angle of 90° requires zero minutes and seconds. Display rounding includes any carry to the next minute or degree.

The reciprocal heading is not generally the initial return bearing between distant geographic coordinates. A geodesic can have different azimuths at its endpoints; this calculator does not solve that two-location problem or convert between true, grid and magnetic north.

Example Problem #1:

  1. First, determine the current bearing (degrees).
    • The current bearing (degrees) is given as 50.
  2. Finally, calculate the Reverse Bearing using the equation above: 

RB = CB + 180

The values given above are inserted into the equation below and the solution is calculated:

RB = 50 + 180 = 230 (degrees)

Example Problem #2: 

For this problem, the variables required are provided below:

current bearing (degrees) = 80

Test your knowledge using the equation and check your answer with the calculator above.

RB = CB + 180 = ?

RB = 80 + 180 = 260 (degrees)