A map, a compass and the real world don't quite agree on where “north” is. True north is the geographic north pole. Grid north is the direction the vertical grid lines point on your map (identical to true north only along the map's central meridian). Magnetic north is where your compass needle actually points, and drifts over time. Enter one known bearing below, plus your declination and grid convergence, to get the other two.
Magnetic declination is the angle from true north to magnetic north
(positive if magnetic north is east of true north) — look it up for your location
and date, e.g. via NOAA's calculator.
Grid convergence is the angle from true north to grid north (positive if
grid north is east of true north) — usually printed in your map's margin, and 0°
if you're not working from a projected grid.
Grid bearing
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True bearing
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Magnetic bearing
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