Aviation Training Experts

Aviation Training Experts™

Compass Deviation Calculator

Convert magnetic heading to compass heading, or compass heading to magnetic, using east or west deviation. This free aviation calculator helps pilots with heading corrections, navigation, and flight training.

Calculate Compass Deviation Conversion

Enter a heading, deviation, and conversion type to calculate the corrected compass or magnetic heading.

Magnetic / Compass Conversion

How It Works

Magnetic to Compass:
Add East, Subtract West
Compass to Magnetic:
Subtract East, Add West
Memory Aid:
TVMDC: True, Variation, Magnetic, Deviation, Compass

This calculator applies standard aviation deviation rules and normalizes the result to a heading between 000° and 360°.

What Is Compass Deviation?

Compass deviation is the error in the magnetic compass caused by magnetic fields within the aircraft. Electrical systems, metal structure, avionics, and other onboard influences can make the compass read slightly different from magnetic heading.

Because of this, pilots use deviation corrections along with variation corrections to convert between true, magnetic, and compass headings.

Why Pilots Use a Compass Deviation Calculator

Compass Deviation FAQ

Is deviation the same as variation?

No. Variation is the difference between true north and magnetic north. Deviation is compass error caused by the aircraft itself.

Where do pilots find deviation values?

Deviation values are often found on the aircraft compass correction card near the magnetic compass.

Why does deviation change?

Deviation can vary depending on aircraft equipment, electrical systems, and heading. That is why compass correction cards show different values for different headings.

Why is this useful in aviation?

Understanding compass deviation helps pilots convert headings accurately and use the magnetic compass more effectively for navigation and training.