Vimshottari Dasha Explained: The 120-Year Planetary Period System

A dasha is a planetary period. The Vimshottari system — "one hundred and twenty" — assumes a human lifespan of 120 years and divides it among the nine grahas in a fixed sequence. At any moment in your life you are in the main period (Mahadasha) of one planet and in a sub-period (Antardasha) of another. The planet ruling the period sets a theme for that stretch, coloured by how it is placed in your birth chart.

The periods always follow the same order, and the lengths add up to 120 years:

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

The starting point is the Moon's nakshatra at birth. The 27 nakshatras are assigned to the nine planets in a repeating sequence of three — so each planet rules three nakshatras. A Moon in Ashwini, Magha or Mula begins with Ketu; Bharani, Purva Phalguni or Purva Ashadha with Venus; Krittika, Uttara Phalguni or Uttara Ashadha with the Sun; Rohini, Hasta or Shravana with the Moon; Mrigashira, Chitra or Dhanishta with Mars; Ardra, Swati or Shatabhisha with Rahu; Punarvasu, Vishakha or Purva Bhadrapada with Jupiter; Pushya, Anuradha or Uttara Bhadrapada with Saturn; and Ashlesha, Jyeshtha or Revati with Mercury.

Nobody is born exactly at the beginning of a nakshatra, so the first period is only partly left. The balance is proportional to how much of the nakshatra the Moon still has to travel. If the Moon has crossed a quarter of its nakshatra, three quarters of the first Mahadasha remain at birth.

Each Mahadasha is divided into nine sub-periods, one for each planet, starting with the Mahadasha planet itself and following the same order. The length of a sub-period is proportional: the Mahadasha years times the sub-period planet's years, divided by 120. For example, Jupiter Mahadasha with Saturn Antardasha lasts 16 × 19 ÷ 120 ≈ 2.53 years, or about two years and six and a half months. Finer levels — Pratyantardasha and below — divide each sub-period the same way.

Astrologers look at the period lord's sign, house, dignity and aspects; the houses it rules; and its relationship to the Mahadasha lord in the case of a sub-period. A well-placed planet is expected to give its results more easily in its period, and a difficult placement is described as a period demanding more effort. Transits — the planets' current movements — are read alongside the dasha for timing.

Two calculators can show dasha dates a few days apart from each other, and sometimes more. The two main reasons are the Moon's exact longitude at birth — a few minutes of birth-time error moves the Moon by a fraction of a degree, and the dasha balance depends on it — and the length assumed for a "year". Traditions use a 360-day savana year, the 365.25-day Julian year or the true sidereal solar year of about 365.256 days; over a lifetime of decades these produce a difference of days to weeks. This site uses the sidereal solar year.

Dasha is a traditional framework for thinking about timing, not a scientifically established predictor. It is best used as a reflective tool, alongside professional advice for real decisions.