Magnetic North vs true North in Vastu: which to use

True North is the direction to the geographic North Pole, the one maps are drawn to. Magnetic North is where a compass needle points, set by the Earth's magnetic field. The angle between them is the magnetic declination. NOAA defines it as positive when magnetic North lies east of true North and negative when it lies west [2].

Declination is not fixed. The magnetic field changes with time, which is why maps print a declination value and need to revise it [3]. NOAA reports the North Magnetic Pole drifting across the Canadian Arctic, most recently at about 55 km a year towards the north-north-west [4].

The standard model for declination is the World Magnetic Model. WMM2025 was released on 17 December 2024 and is valid to the end of 2029, and a new model is issued every five years because the field keeps changing [5]. It is the model used for navigation by the UK Ministry of Defence, the US Department of Defense and NATO [6], and Android's own declination function is built on an earlier version, WMM-2020 [7].

These values come from NOAA's calculator for WMM2025, as checked on 2 Oct 2026 and listed in Vastu16's method [5]. Declination drifts by a fraction of a degree a year, so recheck before relying on an old number.

A 16-zone zone is 22.5 degrees wide and an 8-direction zone is 45 degrees [1]. So a 13 to 15 degree gap is more than half a 16-zone zone. Families in the USA will find more on our page on Vastu for homes in the USA.

To turn a compass bearing into a true bearing, add the declination, counting east as positive and west as negative. True bearing equals compass bearing plus declination.

Seattle, main door. A compass reads 95 degrees to the door from the centre of the home. Add 14.9 and the true bearing is about 110 degrees. In the 16-zone school that moves the door from E (good) to ESE (avoid, 3 of 5). In the 8-direction school both bearings sit in E, rated good [1].

New York, toilet. A compass reads 110 degrees. Add minus 12.5 and the true bearing is 97.5 degrees. In the 16-zone school that moves the toilet from ESE (rated good for a toilet) to E (avoid, 2 of 5). In the 8-direction school both sit in E, avoid 2 of 5.

Delhi, any room. Add 1.3 degrees. Only a room within 1.3 degrees of a zone line changes. Vastu16 already flags any room within 5 degrees of a line, because a small error in North would change it [1].

Local magnetic noise is often bigger than the declination in India. NOAA notes local anomalies of 3 to 4 degrees are not uncommon [8].

The classical texts find direction from the sun, not a magnetic needle. The Mayamata (6.1 to 13) sets up a gnomon, a vertical pole, draws a circle round it, and marks where the morning and evening shadows touch the circle; the line between the two points runs east to west [9]. The Manasara (VI.1 to 30) describes the same method with a larger circle: its radius is twice the gnomon's length, where the Mayamata's radius equals the gnomon's length [9][10].

A shadow-based east-west line points to true directions, not magnetic ones. Both texts add a correction called apacchaya, but Dagens, citing Yano, notes that it is a way of expressing noon-shadow length and has nothing to do with orientation [9].

So the texts give no basis for magnetic North. Reading a compass on site is practical, and in India it lands close to true North. A gnomon line and a satellite map agree with each other. A compass agrees with both once you correct for declination.

We use the satellite map match as the reference, because it gives true North. The phone compass reading is magnetic and is not yet corrected for declination, so we treat it as a check [1]. North confidence is rated high when the map and the compass agree within 8 degrees, medium when only one is done or they differ by 8 to 15 degrees, and low beyond that. Compass readings more than 10 degrees apart are rejected.

In India, a good compass reading and the map usually agree within that 8 degrees. In New York or Seattle, they will not, because of declination alone. Set North from the map there. The full rules are on our methodology page.

Tradition

• Direction set by the gnomon's shadow: Mayamata 6.1 to 13 [9]; Manasara VI.1 to 30 [10].
• Zone widths and ratings under both schools: Vastu16's rule table, a draft pending consultant review [1].

Physical fact

• Declination is the angle between magnetic and true North, positive east: NOAA [2].
• The field changes, and declination values need revising: BGS [3]; NOAA on pole drift [4].
• WMM2025 is valid to the end of 2029 and is the navigation standard: NOAA [5]; BGS [6].
• City declinations: NOAA calculator, WMM2025, checked 2 Oct 2026 [5].

Our free tool lets you verify North by satellite map and compass, then read every room. It shows each room's zone under both schools and how confident the North is. It does not yet correct the phone compass for declination, so in the USA, set North from the map.