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 latitude in degrees (-90 to 90)
• \( longitude \) — Geographic longitude in degrees (-180 to 180)
• \( altitude \) — Height above sea level in meters
• \( date \) — Year for which to calculate the 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 of Magnetic Variation

Details: Magnetic variation is crucial for navigation, aviation, surveying, and other applications where precise directional measurements are needed.

4. Using the Calculator

Tips: Enter latitude (-90 to 90), longitude (-180 to 180), altitude in meters, and the year (1900-2100) for which you want the calculation.

5. Frequently Asked Questions (FAQ)

Q1: How often does magnetic variation change?
A: The WMM is updated every 5 years to account for the changing magnetic field.

Q2: Why is altitude important?
A: The Earth's magnetic field strength decreases with altitude, affecting the variation.

Q3: What's the typical variation in the UK?
A: Currently about 0-2° West, decreasing by about 0.1° per year.

Q4: How accurate is this calculator?
A: Using the official WMM, accuracy is typically within 0.5° for most locations.

Q5: When is magnetic variation most important?
A: Critical for compass navigation, especially when precision of 1-2° matters.