Ayanamsa

Ayanamsa is the Sanskrit term for the precession offset that separates the tropical and sidereal zodiacs. Because Earth's axis slowly wobbles over a 26,000-year cycle, the position of the spring equinox drifts backward through the constellations at roughly one degree every 72 years. The ayanamsa is the accumulated drift since some agreed-upon reference point in the past.

There is no single agreed-upon ayanamsa value. The most widely used in modern Vedic astrology is the Lahiri ayanamsa (also called the Chitrapaksha ayanamsa), adopted as the official Indian government standard in 1955. As of 2026, the Lahiri ayanamsa is approximately 24 degrees and 15 arcminutes. Other ayanamsas in use include Raman, Krishnamurti, and Fagan-Bradley, each with slightly different reference epochs.

To convert a tropical position to sidereal, you subtract the ayanamsa. A planet at 20 degrees tropical Cancer becomes approximately 25 degrees sidereal Gemini using Lahiri. The conversion is purely mathematical and reversible — both systems describe the same physical position in the sky, just measured against different reference points.

For ZODIA users: ZODIA uses the tropical zodiac, so ayanamsa does not enter our calculations. If you have had a Vedic chart cast and are wondering why your placements differ from your ZODIA chart, the answer is the ayanamsa offset. Both charts are correct within their own traditions.