Heading & Course Converter

Convert between true, magnetic, and compass headings using magnetic variation and compass deviation. The TVMDC chain made easy.

Convert Direction

True Course / Heading

Magnetic Variation

US: −20°W (Pacific NW) to +15°E (New England)

Compass Deviation

Typically ±2° to ±5°

Tab to move between fields

True Course / Heading

90°

Magnetic Heading

80°

Compass Heading

78°

Reciprocal (True)270°

Variation10°E

Deviation2°E

How to Use This Calculator

Select conversion direction: True→Compass or Compass→True.
Enter the starting heading value.
Enter magnetic variation from sectional chart isogonic lines (East = positive, West = negative).
Enter compass deviation from the correction card in your aircraft.
Remember: TVMDC — True Virgins Make Dull Companions.

How the result changes with True Course / Heading

True Course / Heading	True Course / Heading	Magnetic Heading	Compass Heading
180	180°	166°	164°
270	270°	286°	289°
360	0°	0°	359°

Convert Direction: Choose which direction to convert.
True Course / Heading: Heading or course referenced to true north (from charts).
Compass Heading: Heading shown on the magnetic compass in the cockpit.
Magnetic Variation: Positive = East variation, Negative = West variation. Found on sectional chart isogonic lines.
Compass Deviation: Deviation for the current heading from your aircraft's compass correction card.

True Course/Heading
Given
90° = 90° True
Magnetic Heading
Magnetic = True − East Variation (or + West Variation)
90° − (+10°) = 80° Magnetic
Compass Heading
Compass = Magnetic − East Deviation (or + West Deviation)
80° − (+2°) = 78° Compass
Reciprocal Heading
Reciprocal = True ± 180°
90° + 180° = 270° True