Magnetic Declination

True = Magnetic \pm declination (East is plus to mag \to true)

Declination is the angle from true north to magnetic north. ‘East is least, west is best’ is a memory aid: true = mag + east (or − west) when going mag→true. Annual change accumulates since the map date.

$δ$: Declination

Step-by-step solved example

Magnetic bearing N 20° E, declination 8° E. True bearing?

True vs magnetic north — declination east or west.

1. Add east
True = 20°+8° = N 28° E.
2. Azimuth
True azimuth 28° from north.

Answer: N 28° E

10 practice questions

0/10 correct

1.West declination 10°, mag N 5° E: true is

2.Agonic line has

3.Grid north vs true north is

4.A compass needle points to

5.If declination increased 0.1° E per year for 20 years since the map, add

6.Back bearing of S 40° W is

7.Azimuth 350° is a bearing

8.Isogonic lines join

9.Local attraction (ore, fence) makes

10.True azimuth 80°, δ=10° W: magnetic azimuth ≈