Magnetic Variation Converter
True ↔ Magnetic ↔ Compass. Enter the variation from the sectional or VFR chart and convert headings in either direction. East is least, west is best.
Inputs
0-360. From your chart, GPS, or DG.
Read from the dashed magenta isogonic line on your sectional or VFR chart.
From the aircraft's compass correction card. Usually ±2-5°.
Mnemonic
East is least · West is best
East variation makes magnetic less than true. West variation makes magnetic more than true.
Enter heading + variation
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Variation is signed: W adds to true, E subtracts.
Full chain
Add compass deviation to compute.
About this calculator
Magnetic variation is the angular difference between true north and magnetic north at your location, drawn as dashed magenta isogonic lines on sectional and VFR charts. It changes by a few degrees per decade as Earth's magnetic field drifts, so always use the current chart.
Internally we store variation as signed (positive = West, negative = East), which lets the same formula work both ways: MAG = TRUE + VAR · TRUE = MAG − VAR. Deviation is the per-aircraft compass-card correction posted near the magnetic compass; it's typically ±2-5° and changes with heading.
Trim
Navigation fundamentals are lesson one of cross-country. Trim tracks the ground school + flight hours that build toward the solo XC sign-off.
Flight training management for independent CFIs.