1. What is Magnetic Variation?

Magnetic variation (also called magnetic declination) is the angle between magnetic north and true north. It varies by location and changes over time due to movements in Earth's magnetic field.

2. How Does the Calculator Work?

The calculator uses the World Magnetic Model (WMM):

Where:

• Latitude — Geographic coordinate (-90° to 90°)
• Longitude — Geographic coordinate (-180° to 180°)
• Altitude — Height above sea level in meters
• Date — Year for which to calculate variation

Explanation: The WMM is a joint product of the United States' National Geospatial-Intelligence Agency (NGA) and the United Kingdom's Defence Geographic Centre (DGC).

3. Importance for Aviation

Details: Magnetic variation is crucial for aviation navigation as it affects compass readings. Pilots must account for it when converting between true and magnetic headings.

4. Using the Calculator

Tips: Enter coordinates in decimal degrees (positive for N/E, negative for S/W). Altitude should be in meters above sea level. Date should be the year of interest.

5. Frequently Asked Questions (FAQ)

Q1: How often does magnetic variation change?
A: The WMM is updated every 5 years to account for secular variation in Earth's magnetic field.

Q2: Why is altitude important?
A: The magnetic field strength decreases with altitude, though this has minor effect on variation.

Q3: What's typical variation range?
A: Currently ranges from about 20° east to 30° west depending on location.

Q4: How accurate is this calculator?
A: The WMM provides accuracy of about 30 minutes of arc for declination.

Q5: Where is variation zero?
A: Along agonic lines where magnetic and true north align (changes over time).