Ayanamsa Explained: Lahiri Value 2026–28 and What It Shifts

The ayanamsa (अयनांश) is the number of degrees separating the two zodiacs. The tropical zodiac, used in western astrology, starts at the point where the Sun stands at the March equinox. The sidereal zodiac of Vedic astrology starts from a point fixed against the stars. Because the equinox point slides slowly backwards against the stars, the gap between the two starting points grows every year, and every sidereal position in a kundli is the tropical position minus that gap.

So the ayanamsa is not a correction applied now and then. It is part of every planet, nakshatra and lagna on the page. This article gives the value the site computes with, shows how it is calculated, and then measures what a different value would move.

The Lahiri Value, 2026 to 2029

The site uses the Lahiri, or Chitrapaksha, ayanamsa. Its value at the start of each year, at midnight IST on 1 January:

It grows by about 50.3″ (arcseconds) a year, which is one degree in roughly 72 years. Between the J2000 epoch and 1 January 2026 it grew by 0°22′. A chart cast for a birth decades ago should therefore use the ayanamsa of the birth date, not today’s; any software that takes the date as input does this for you.

How It Is Calculated

The expression in the site’s code is short. Take the value at the standard epoch J2000 (noon on 1 January 2000), 23.856808°, and add the general precession accumulated since then: 5029.0966″ per Julian century, plus a small 1.11113″ term that grows with the square of the centuries. Time is measured in Terrestrial Time, which is why the code adds ΔT, about 75 seconds in 2026, before evaluating it. The sidereal longitude of any body is then its apparent tropical longitude minus this number. Most ayanamsas grow at very nearly this rate. Where they mainly disagree is the starting value, the number fixed at the epoch.

Why “Chitrapaksha”

That starting value is not arbitrary. Lahiri’s definition anchors the zodiac to the star Chitra (Spica), placing it at 180°, the line between Virgo and Libra. The nakshatra named after the star runs Virgo 23°20′ – Libra 6°40′, so the line falls exactly at its middle, and the star sits at the centre of its own nakshatra. That is the “Chitra side” the name refers to. In the 1950s the Calendar Reform Committee set up by the Government of India, chaired by the physicist Meghnad Saha, adopted N. C. Lahiri’s value for the national calendar.

Lahiri, Raman, KP and the Others

Other ayanamsas anchor the zodiac somewhere else. As usually quoted, B. V. Raman’s value runs about a degree and a half below Lahiri’s. The Krishnamurti (KP) value sits only a few arcminutes below it. The Fagan–Bradley value used in western sidereal astrology is a little under a degree above. Treat these as orders of size only. Each system has its own epoch figure, and this site computes only Lahiri’s.

“Which ayanamsa is most accurate?” has no measured answer. The precession rate is measured astronomy, and the systems differ on it only slightly. The starting point is a definition, a choice of where the sidereal zodiac begins, and no observation picks one definition over another. What can be measured is the practical question: how much does a given difference change a chart?

What One Degree of Difference Moves

A different ayanamsa shifts every sidereal position by the same amount, so a planet near a sign line can change sign while one in mid-sign does not. Read in time, the shift moves each sign change by however long the planet takes to cover the difference. These are the speeds at the actual crossings in the site’s 2026–2028 ingress table:

The direction is fixed by the subtraction. A smaller ayanamsa leaves a larger sidereal longitude, so a planet moving forward reaches each sign line sooner. A larger one makes it later. With Saturn crossing at about 0.10° a day, a degree of difference is roughly 10 days, which is why almanacs on different ayanamsas can disagree about a slow planet’s sign change by a week or more while agreeing to within a day on the Sun’s. Saturn crosses much more slowly than that when it is close to a station, and the gap grows with it.

For a birth chart the lagna row matters most. A lagna within about a degree and a half of a sign edge can fall in different signs under Lahiri and Raman, the same uncertainty as a few minutes of birth time. The lagna and navamsa durations page measures how quickly each varga changes, and the rashi sandhi page covers a planet sitting at the very start or end of a sign.

Tithi Does Not Depend on It; Yoga Depends on It Twice

The panchang limbs react to the ayanamsa in three different ways, and the arithmetic shows why. A tithi is the Moon’s distance ahead of the Sun in steps of 12°. Both longitudes lose the same ayanamsa, so it cancels, and the tithi is identical in every system, tropical included. The karana is half a tithi and behaves the same way. The nakshatra is the Moon’s own sidereal longitude, so it moves with the ayanamsa one-for-one. The panchang yoga is the sum of the Sun’s and Moon’s longitudes, so the ayanamsa enters twice. Read from tropical longitudes, the yoga would come out about four yogas off. Two panchangs that agree on every tithi can still differ on when a nakshatra or a yoga begins.

Tropical and Sidereal Sun Signs

In 2027 the Sun reaches tropical 0° Aries on 21 March 2027, the March equinox. It reaches sidereal Aries on 14 April 2027, 24 days later, the time it takes to cover the ayanamsa at about a degree a day. Every sign boundary is offset the same way, which is why a western Sun sign is often one sign ahead of the Vedic one. The Sun sign and Moon sign page covers what each sign is used for, and the Sun sign calculator gives yours.

What This Page Does Not Claim

It does not say any ayanamsa is the true one, or that a chart cast with one is more reliable than with another. Those are disputes between schools, and choosing an ayanamsa is choosing a school’s definition. What the page does claim is narrower: what value this site uses, how it is computed, and how far a different choice moves each part of the chart. The figures the site prints for transits, such as Jupiter’s Leo spells in 2026–28, are all Lahiri.

In Brief

• Lahiri on 1 January 2026: 24°13′12″, growing about 50.3″ a year
• Anchor: Chitra (Spica) at 180°, the middle of its nakshatra
• One degree of difference: lagna about 4 minutes, Moon about 109 minutes, Sun ingress about a day, Saturn ingress about 10 days
• Unaffected: tithi and karana. Affected once: nakshatra. Twice: yoga

In Hindi: अयनांश क्या है: लाहिरी अयनांश का मान 2026–29.