1. What is Magnetic Variation?

Magnetic variation (also called declination) is the angle between magnetic north and true north. It changes depending on your location on Earth and changes slowly over time.

2. How Does the Calculator Work?

The calculator uses the World Magnetic Model (WMM) which is a standard model of Earth's magnetic field:

Where:

• Latitude — Your north-south position on Earth (-90° to 90°)
• Longitude — Your east-west position on Earth (-180° to 180°)
• Altitude — Your height above sea level in meters
• Date — The year for which to calculate the variation

Explanation: The WMM uses complex mathematical formulas to predict how Earth's magnetic field changes at different locations and times.

3. Importance of Magnetic Variation

Details: Knowing magnetic variation is important for navigation, especially when using a compass. It helps convert between magnetic directions and true directions on maps.

4. Using the Calculator

Tips: Enter your latitude and longitude in decimal degrees, altitude in meters, and the year you want the calculation for. The calculator will estimate the magnetic variation at that location and time.

5. Frequently Asked Questions (FAQ)

Q1: Why does magnetic variation change over time?
A: Earth's magnetic field is generated by moving molten metal in the outer core, which changes slowly over time.

Q2: How accurate is this calculator?
A: The WMM is very accurate for navigation purposes, typically within 1 degree of the actual variation.

Q3: Do I need to know my exact location?
A: More precise coordinates give more accurate results, but approximate values will still give a good estimate.

Q4: Why does altitude matter?
A: Earth's magnetic field strength changes with altitude, though the effect on variation is small.

Q5: How often is the WMM updated?
A: NOAA updates the WMM every 5 years, with the next update scheduled for 2025.