Magnetic Heading Calculator

Work out magnetic heading instantly with clear inputs, formula shown and shareable results.

About Magnetic Heading Calculator

True heading converts to magnetic by removing variation (east variation is subtracted, west variation added — the classic 'east is least, west is best'), and magnetic converts to compass by removing the deviation from the aircraft's compass correction card.

Formula

Heading chain

Magnetic = True - variation (east +); Compass = Magnetic - deviation

Worked example

With the default values below, Magnetic Heading Calculator returns Magnetic heading of 99.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

True heading: 95 °
Magnetic variation (east positive): -4 °
Compass deviation: 2 °

Results

Magnetic heading: 99.0 °
Compass heading: 97.0 °
Total correction applied: 2.00 °

Step by step

1Values used
2Heading chain
3Magnetic heading= 99.0 °
4Compass heading= 97.0 °
5Total correction applied= 2.00 °

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.

Frequently Asked Questions

Which sign convention is used here?

East variation is entered as a positive number and is subtracted from true heading; west variation is negative and therefore adds.

Where does deviation come from?

From the compass swing recorded on the aircraft's deviation card. It is caused by the aircraft's own magnetic and electrical fields and changes with heading.