How to Correct a Compass to Get True North

A compass is a basic tool used by hikers, rescue searchers and adventurers around the world. It helps to find direction. Coupled with a map, you can chart a course and follow it to your destination. Compasses respond to the magnetic field of the Earth and the needle points towards the magnetic north pole. There exist two north poles on the Earth; one depends on geography and the other on the magnetic field of the Earth. To correct the reading of a compass to indicate true north -- the one based on geography -- the compass is marked with an offset. Every topographical map shows a declination symbol that denotes the correction to magnetic north to find true north.

Things You'll Need

  • Compass
  • Strip of tape
  • Small Screwdriver
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Instructions

    • 1

      Examine your compass and discern if it has a movable bezel on the outside of the compass face. Marks on the bezel allow the user to follow a course in reference to the point of the compass needle. Look at the bezel to find out how to rotate it. Most bezels utilize a setscrew or latch to hold the bezel in place.

    • 2

      Find the declination symbol on your map. Make note of the number of degrees true north is from magnetic north and whether true north is to the east or west of magnetic north.

    • 3

      Unlock the bezel by lifting the latch or loosening the setscrew. Rotate the bezel to the degree reading for true north. Reset the latch or setscrew to lock the bezel in place.

    • 4

      Use a piece of tape to mark true north on your compass if it doesn't possess a bezel. Place a small piece of tape on the face of the compass from the center to the edge at the proper declination for true north. When taking a bearing or direction measurement, move the needle to the tape. All readings based on the tape will be true north readings, because the true north correction has been taken into account in the compass.