The Vimshottari cycle

A kundli shows where the grahas stood at birth. The tradition also asks a second question: when does each graha’s theme come forward in a life? Its answer is the system of dashas, planetary periods that divide a lifetime into chapters, each ruled by one graha. This lesson explains how the most widely used system, the Vimshottari dasha, is built and calculated.

What a dasha is

Dasha means “state” or “condition”. A mahadasha is a major period ruled by one graha, the dasha lord. Brihat Parashara Hora Shastra describes many dasha systems, among them Ashtottari and Yogini, and names Vimshottari as the principal one. Vimshottari means “one hundred and twenty”, the total length of the cycle in years. It is the system shown in most Indian horoscopes and on this site.

Nine lords in a 120-year cycle

The nine grahas follow one another in a fixed order, and each rules for a fixed number of years:

• Ketu 7, Venus 20, Sun 6
• Moon 10, Mars 7, Rahu 18
• Jupiter 16, Saturn 19, Mercury 17

The years add up to 7 + 20 + 6 + 10 + 7 + 18 + 16 + 19 + 17 = 120. After Mercury the order returns to Ketu. Nobody lives through the whole cycle from its start, because, as you will see, a life begins partway through one of the periods.

The nakshatra lords

The same nine lords, in the same order, are assigned to the 27 nakshatras, starting with Ashwini. Nine lords over 27 nakshatras means the sequence runs three times round the zodiac: Ashwini is ruled by Ketu, Bharani by Venus, Krittika by the Sun, and so on, until Revati, the 27th, is ruled by Mercury.

• Ketu: Ashwini, Magha, Mula
• Venus: Bharani, Purva Phalguni, Purva Ashadha
• Sun: Krittika, Uttara Phalguni, Uttara Ashadha
• Moon: Rohini, Hasta, Shravana
• Mars: Mrigashira, Chitra, Dhanishta
• Rahu: Ardra, Swati, Shatabhisha
• Jupiter: Punarvasu, Vishakha, Purva Bhadrapada
• Saturn: Pushya, Anuradha, Uttara Bhadrapada
• Mercury: Ashlesha, Jyeshtha, Revati

The first dasha and its balance

The first mahadasha of a life is ruled by the lord of the nakshatra the Moon occupies at birth, the janma nakshatra. Because the Moon is usually partway through that nakshatra, only the unused part of the period remains. This remainder is the balance of dasha at birth: the fraction of the nakshatra still to be crossed, multiplied by the lord’s years.

Example 1: the Moon is at 20°00′ Aries. Bharani runs from 13°20′ to 26°40′ Aries, so the Moon is in Bharani, ruled by Venus. It has crossed 20°00′ − 13°20′ = 6°40′ of the nakshatra’s 13°20′, exactly half, and half remains. The balance is ½ × 20 = 10 years of Venus. The Sun’s 6 years follow, so this person’s Sun dasha runs from age 10 to 16, the Moon’s from 16 to 26, Mars from 26 to 33 and Rahu from 33 to 51.

Example 2: the Moon is at 5°00′ Taurus. Krittika runs from 26°40′ Aries to 10°00′ Taurus, so the Moon is in Krittika, ruled by the Sun, with 5°00′ of the nakshatra left. The remaining fraction is 5°00′ ÷ 13°20′ = 0.375, and the balance is 0.375 × 6 = 2.25 years: 2 years and 3 months of the Sun, followed by the Moon’s full 10 years.

The example above shows the mahadasha and antardasha running now and the next ones, calculated from the Moon of your saved birth details, or from the sky right now if none are saved. The dates are calculation; what a period is said to bring is traditional interpretation.

How long is a dasha year?

To turn dasha years into calendar dates, a length must be chosen for the year. This site uses 365.25 days, close to the solar year. Some traditions use a 360-day year instead. The difference grows with time: a 10-year balance differs by 10 × 5.25 = 52.5 days, and the full 120-year cycle by 630 days, about 1.7 years. Neither is a mistake; it is a tradition difference, and the methodology page states the choice.

The dasha dates depend on the Moon’s exact degree. The Moon moves about 13° a day, roughly 0.55° an hour, so an hour’s error in the birth time shifts the Moon by about 0.55°. In a Venus nakshatra that changes the balance by 0.55 ÷ 13.33 × 20 ≈ 0.8 years, about 10 months. Dasha dates are therefore only as good as the recorded birth time.