What is Magnetic Declination?
Magnetic declination is the difference between magnetic north (where your compass points) and true geographic north. This angle varies by location and changes slowly over time. If you don't account for declination, your compass bearing can be off by several degrees — enough to walk miles past your destination in wilderness terrain.
East vs West Declination
East declination: Compass points west of true north. Add the declination to your compass bearing to get true north. Example: compass bearing 90° + 10° East = 100° true bearing.
West declination: Compass points east of true north. Subtract the declination from your compass bearing to get true north. Example: compass bearing 90° - 15° West = 75° true bearing.
💡 Set It and Forget ItMany compasses have a adjustable declination mechanism. Set your compass to account for local declination, and all readings will automatically be corrected. Otherwise, always apply the correction manually.