Global sample layer
West declination: magnetic north is west of true northNear zero declinationEast declination: magnetic north is east of true northCaution zone: 2,000 ≤ H < 6,000 nTBlackout zone: H < 2,000 nT; compass unreliable
What the “lie” actually is
A compass does not point at one magnetic pole. Its needle aligns with the local horizontal magnetic field. Declination is the local angle from true north to that horizontal field: east is positive, west is negative. Use True heading = Magnetic heading + D.
WMM2025 models the long-wavelength internal field. It does not include all crustal, ionospheric or magnetospheric effects, nearby steel, vehicles or other local magnetic disturbances. NOAA notes that local declination anomalies of several degrees occur and rare anomalies can exceed 10°.