Estimate Earth’s magnetic field elements for any latitude, longitude, altitude, and year using a NOAA-style quick model. Results are useful for orientation, educational projects, and rough planning.
What This NOAA Magnetic Field Calculator Does
The Earth’s magnetic field is not constant. It changes with your location, your elevation, and time. This calculator estimates core magnetic values commonly shown in NOAA and World Magnetic Model tools: declination, inclination, horizontal intensity, total intensity, and vector components.
If you work with a compass, drone flight planning, GIS workflows, surveying notes, or geophysics exercises, these values help you align magnetic north with true north and understand local field geometry.
Inputs You Need
Latitude and Longitude
Enter coordinates in decimal degrees. North and East are positive values. South and West are negative values. For example, New York City is roughly 40.7128, -74.0060.
Altitude
Altitude is entered in kilometers above sea level. For most ground-level compass work, use 0 km. Aircraft and high-altitude balloons can use larger values.
Decimal Year
Magnetic field models drift over time due to changes in Earth’s outer core. Decimal year lets you represent dates like 2026.25 (about early April 2026).
How to Read the Results
- Declination (D): Angle between true north and magnetic north. East is positive, West is negative.
- Inclination (I): Dip angle of the field into Earth. Positive means field points downward.
- Horizontal Intensity (H): Strength of the magnetic field in the horizontal plane (nT).
- Total Intensity (F): Full field strength magnitude (nT).
- X, Y, Z Components: North, East, and Down components of the field vector.
Where This Is Useful
- Compass correction in field operations and hiking logs
- Drone and UAV orientation checks
- Surveying prep before data collection
- Educational physics and geoscience labs
- Software testing for geomagnetic-aware apps
Model Notes: NOAA vs Quick Browser Estimate
NOAA’s official calculators use high-order geomagnetic models (such as WMM/IGRF spherical harmonics), including more detail than a simple dipole approximation. This page intentionally keeps calculations local and fast in your browser.
That means this tool is excellent for understanding trends and generating quick estimates, but it is not a substitute for certified aviation, marine, defense, or precision survey requirements. For authoritative values, use NOAA’s official calculator at NOAA Geomagnetic Calculators.
Tips for Better Accuracy in Practice
- Use precise coordinates from GPS rather than city-center approximations.
- Set altitude appropriately if you are significantly above sea level.
- Update the year for historical or future estimates.
- Keep magnetic interference away from your compass (phones, steel objects, batteries).
FAQ
Is this the official NOAA magnetic field calculator?
No. This is a NOAA-style educational estimator designed to run entirely in one HTML page.
Can I use these values for chart publication?
For published or regulated data products, you should rely on official NOAA/WMM outputs.
Why does declination vary with time?
Molten metal flow in Earth’s outer core changes the magnetic field slowly over years, causing north direction and field strength to drift.