What is an IGRF calculator?
An IGRF calculator estimates Earth’s magnetic field at a specific place and time. IGRF stands for International Geomagnetic Reference Field, a global scientific model maintained by international experts. It is widely used in navigation, geophysics, aerospace engineering, and magnetic survey correction.
The magnetic field is not static. It changes with both location and time, so an IGRF calculator typically needs:
- Latitude and longitude
- Altitude
- Date or decimal year
How this calculator works
This page computes a fast approximation using the dominant dipole terms
(g10, g11, h11) interpolated through time. That gives useful, intuitive values for:
- X: North component
- Y: East component
- Z: Down component
- H: Horizontal intensity
- F: Total intensity
- D: Declination (angle from true north)
- I: Inclination or dip angle
For operational-grade work, use the full IGRF spherical-harmonic model (higher-degree coefficients). This simplified version is best for education, quick checks, and understanding trends.
Dipole coefficients used
| Year | g10 (nT) | g11 (nT) | h11 (nT) |
|---|---|---|---|
| 2000 | -29619.4 | -1728.2 | 5186.1 |
| 2005 | -29554.6 | -1669.0 | 5078.0 |
| 2010 | -29496.6 | -1586.4 | 4944.3 |
| 2015 | -29441.5 | -1501.8 | 4796.2 |
| 2020 | -29404.8 | -1450.9 | 4652.5 |
| 2025 | -29376.3 | -1413.9 | 4523.0 |
| 2030 | -29347.8 | -1376.9 | 4393.5 |
How to use this page
Step-by-step
- Enter latitude in decimal degrees (north positive, south negative).
- Enter longitude in decimal degrees east (west can be negative).
- Enter altitude in kilometers.
- Enter decimal year (for example, mid-2026 is 2026.5).
- Click Calculate Magnetic Field.
Interpreting key outputs
Declination (D) is especially important for compasses. If D is positive, magnetic north lies east of true north. If D is negative, magnetic north lies west of true north.
Inclination (I) tells you how steeply field lines angle into Earth. Near the magnetic equator, I is near zero. Near magnetic poles, I approaches ±90°.
Practical applications
- Compass correction for field operations
- Drone and robotics heading sanity checks
- Magnetometer baseline comparisons
- Educational demonstrations in Earth science courses
- Preliminary planning for geomagnetic surveys
Limitations and best practices
This is a reduced model that captures large-scale behavior but not all regional detail. Local crustal magnetism, magnetic storms, and man-made interference can cause large deviations from the model.
- Use full IGRF/WMM implementations for production systems.
- Treat values here as first-order estimates.
- For high-accuracy navigation, combine model output with sensor calibration.