How to Calculate Direction & Heading
- 1). Look for a declination reading in the margins of your map. Declination is the difference between magnetic north, which is what a compass uses, and true north, which is what a map uses. Adjust your compass using the declination dial, which should be quite small. If your compass has no declination dial, you can adjust your compass housing east or west the exact number of degrees indicated by your map, after you have a heading. Just remember to redo this step on any further headings you plot. If your map has no declination setting, keep in mind that your direction of travel may be slightly wrong, and use features of the terrain to help you navigate your way.
- 2). Place the map of the area you are in on a flat surface. Place the compass on the map. Different compasses have different designs, but a common one is a rectangular base with a rotating housing, with the compass housing at one end and a direction of travel arrow running from the compass housing to the front of the compass base. This is the kind of compass being used in this example.
- 3). Locate where you are on the map, and place one edge of the back end of the rectangular compass base on that spot. Locate where it is you want to go on the map, and place the front edge of the rectangular base of the compass on that spot. The compass should now be on the map in such a way that, if you had a pen or pencil, you would be able to draw a straight line, using the compass like a ruler, from your current position to your destination.
- 4). Turn the compass housing so that the north to south line is parallel to either the grid lines on the map or the edge of the map. If your map has a compass rose and the direction of north is not the top of the map, then align the north-to-south line on the compass housing in the direction indicated by the compass rose.
- 5). Remove the compass from the map, taking care not to move the compass housing. Hold the compass in your hand, away from your body so that nothing metal on your person interferes with the reading. Align the compass needle with the north-to-south line in the compass housing, with the red section of the needle pointing north. The direction indicated by the direction of travel arrow on the base of the compass is the heading you want to take to get to your destination.
