Ayanamsa Calculator (Lahiri)

The Western zodiac is tied to the seasons — 0° Aries is fixed to the spring equinox. The Vedic zodiac is tied to the actual stars. Because the Earth's axis slowly wobbles (the “precession of the equinoxes”), the equinox drifts against the stars by about 50 arc-seconds a year. The accumulated gap between the two zodiacs is the ayanamsa.

Today that gap is roughly 24 degrees. So a planet near the start of a tropical sign often falls in the previous sidereal sign — which is exactly why many people are, say, a Western Aries but a Vedic Pisces.

Both systems are internally consistent; they just measure from different starting points. Western astrology answers “where is the planet relative to the seasons?”, while Vedic astrology answers “where is the planet relative to the fixed stars?” Subtract the ayanamsa from a tropical position and you get the sidereal one.

There are several ayanamsa definitions, but the Lahiri (Chitrapaksha) ayanamsa is India's official standard, used in the Government of India's Rashtriya Panchang and by our own calculators. Learn more in our guides to Vedic and Western astrology.

The Lahiri ayanamsa is anchored to a star: it fixes Chitra (Spica) near 180° of the sidereal zodiac, which sets where sidereal 0° Aries falls. From that anchor the value at any other date is found by adding the precession that has accumulated — the equinox drifts against the stars by about 50.29 arc-seconds a year.

That works out to roughly 0.014° per year, or about 1° every 72 years. So the figure is not fixed: it was near 23.15° around 1950 and is about 24° today. Pick a date in the calculator above and it applies this model for the exact degrees, minutes and seconds.

Because the gap only grows with time, there was a moment when it was zero — when the spring equinox sat exactly at the start of sidereal Aries and the two zodiacs agreed. For the Lahiri definition that was around 285 CE.

Before that date the sidereal zodiac led the tropical one (a negative ayanamsa); ever since, the gap has widened to today’s ~24°. This is why old texts and modern charts can disagree about a sign unless the ayanamsa is applied for the correct date.

Many ayanamsa definitions have been proposed, but only a few are widely used. They differ by well under a degree, so they usually agree on your sign — and only disagree when a planet sits right at a sign’s edge. This calculator uses Lahiri.

Most Indian Vedic astrology — including this site — uses Lahiri. Because the systems differ by under about a degree, they change a sign only for planets sitting at the very start or end of a sign.

1. 1 Pick a date — today is selected by default.
2. 2 Press Calculate to see the Lahiri ayanamsa in degrees, minutes and seconds.
3. 3 Use the value to convert a tropical (Western) position to a sidereal (Vedic) one by subtracting it.