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In short
The ayanamsa is the angle between the tropical zodiac, which starts at the equinox, and the sidereal zodiac, which is fixed to the stars. Subtracting it turns a tropical position into a sidereal one. It grows slowly every year; this app uses the Lahiri value, 23.85306 degrees at the start of 2000 and a little over 24.2 degrees in October 2026.
What the term means
The ayanamsa is a single angle: how far the start of the tropical zodiac (the March equinox) has moved from the start of the sidereal zodiac (a point fixed to the stars). Subtract it from a tropical longitude and you get a sidereal one. Because the equinox keeps drifting, the ayanamsa grows every year; it is a property of the date, not of the person.
Where the term comes from
The BPHS translation uses the word where a rule needs an equinox-based position: for Ayan Bal the ayanamsa is added to a graha to find its distance from the nearest equinox (Ch. 27 Sl. 15-17), and the Sun's motional rays start from the Sun "with Ayanamsa" (Ch. 28 Sl. 3-4). These passages give no value for it. Advanced Predictive Astrology prints the ayanamsa used for every case chart, says its author follows Lahiri's only, and reports that its Navamsa positions do not change under Krishnamurthy's, which it calls very close to Lahiri's.
How this app computes it
- It uses the Lahiri ayanamsa, as a straight line: 23.85306 degrees at noon on 1 January 2000, plus 0.0139601 degrees a year, which is about 50.26 arc-seconds a year.
- That gives 23.6444 degrees for 19 January 1985 and 24.2269 degrees for 13 October 2026. The ayanamsa calculator takes only a date, because no birth detail enters it.
- Every sidereal position in the app is the tropical position minus this number, so a program using a different ayanamsa moves every graha, and the Ascendant, by the difference between the two. That can change a sign or nakshatra only for a point close to a boundary.
- Krishnamurti Paddhati uses its own ayanamsa. This engine's sub-lord calculation stays on Lahiri, and its code notes that this is why it is not KP.
Pages that use this term
- Why apps disagree on your nakshatra - the ayanamsa as the first suspect.
- What is a Mahadasha - why the dasha needs it.
- Nakshatra sub-lord and birth time - how a different ayanamsa moves a sub-lord.
- The 1st house (Tanu Bhava) - the rising degree made sidereal with it.
- Ayanamsa calculator - the value for any date.
- Methodology - the engine's value checked against a printed chart.
Related terms
- Nirayana - a position with the ayanamsa taken off.
- Sayana - a position with it left on.
- Julian Day - the date input the formula takes.
- Longitude - what it is subtracted from.
Ayanamsa (Lahiri)
The gap between the tropical and sidereal zodiac, for any date you name - no birth details needed.
This date is sent only to compute the answer. Nothing is stored, no account is created, and no email is asked for.