Magnetic Declination Calculator

Our calculator delivers typical accuracy of ±0.5° to ±1.5° for any location within a few hundred kilometres of a reference city — which covers essentially every populated region of the globe. For remote ocean areas or extreme polar latitudes, the accuracy can drift to ±3°.

This is significantly better than a physical baseplate compass can resolve, and more than sufficient for hiking, Vastu, Qibla, solar alignment, antenna aiming, photography, and most architectural work. For aerospace, land surveying, or mission-critical use we always link out to the official NOAA calculator, which evaluates the full spherical-harmonic WMM series.

The Earth’s magnetic field is generated by convecting molten iron in the outer core. That flow is turbulent on geological timescales but clearly observable over years and decades, which is why scientific bodies publish a fresh World Magnetic Model every five years. The magnetic north pole itself has moved more than 2,500 km since the first accurate measurements in 1831, and since the late 1990s it has accelerated from ~15 km/year to ~55 km/year on a path toward Siberia.

For most users the annual drift is small (~0.1° per year in mid-latitudes), so a 2026 reading from Online-Compass.com will remain useful for several years. However, if you are operating in high latitudes above 65°, we recommend recomputing every 12–24 months, since declination changes there can exceed a degree per year.

Yes — the entire Online-Compass.com suite, including this Magnetic Declination Calculator, is delivered as a standard HTTPS web page that runs inside Safari, Chrome, Firefox, Edge, Samsung Internet, and Brave. There is nothing to install, no account to create, and no advertising identifier attached to your session. When you tap Use My Location, your browser asks permission and passes the GPS fix directly to the calculator; the coordinates never leave your device.

For readers coming from our navigation blog, this is the same architecture that powers our live compass — browser-first, sensor-direct, and privacy-respecting by design.

The rule depends on which direction you are converting. To convert a magnetic bearing (what your compass shows) into a true bearing (what your map uses), you add an east declination or subtract a west declination: True = Magnetic + East or True = Magnetic − West. Going the other way (map-to-compass) reverses the sign: Magnetic = True − East or Magnetic = True + West.

Our calculator returns the raw signed value: positive numbers are east declination, negative numbers are west declination. Online-Compass.com’s live compass applies this correction automatically when you enable GPS, so you never have to do the arithmetic yourself in the field.

No. Online-Compass.com runs the declination calculation entirely inside your browser using JavaScript. When you grant geolocation permission, the coordinates are held in page memory, used for the interpolation, and discarded when you close the tab. We do not send your GPS fix to our server, to any analytics provider, or to any advertising network.

This is a deliberate architectural choice. Tools like Qibla Finder, Vastu Compass, Elevation Tool, and the declination calculator all share the same privacy-first promise — your faith, your home alignment, your hiking route, and your coordinates belong to you alone.