Dasha Calculator: Mahadasha and Antardasha Dates

How Vimshottari Dasha Is Calculated

Vimshottari dasha is a 120-year cycle shared between nine planets in a fixed order: Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn and Mercury. Each planet rules three of the 27 nakshatras, and the nakshatras cycle through the nine lords in that same order three times.

Where the cycle starts is decided by the Moon's nakshatra at birth. The lord of the nakshatra the Moon occupied gives the first mahadasha of life. It is not lived in full: the share of the nakshatra the Moon had already crossed is treated as the share of that mahadasha already spent before birth. The remainder — the balance of dasha — starts at birth, and every mahadasha after it runs its full length.

The longest mahadasha is Venus's (20 years) and the shortest is the Sun's (6 years).

Vimshottari Dasha Years of the Nine Planets

Dasha Balance at Birth

The arithmetic, every step shown, on the chart above:

1. The Moon at birth: 201.0432° sidereal.
2. Vishakha runs from 200°00′ to 213°20′; the Moon had crossed 1°03′ of it, which is 7.82% of 13°20′.
3. Jupiter mahadasha lasts 16 years, so 16 × 0.0782 = 1.2518 years had already elapsed before birth.
4. Balance = 16 × (1 − 0.0782) = 14.7482 years, which runs out on 12 January 2005, when Saturn mahadasha begins.

Antardasha and Pratyantardasha Length

Every mahadasha divides into nine antardashas (also called bhuktis), in the same order, starting with the mahadasha's own lord. An antardasha lasts mahadasha years × antardasha lord's years ÷ 120. A pratyantardasha divides an antardasha into nine again by the same rule.

This chart is now in Mercury mahadasha (17 years) and Ketu antardasha (7 years): 17 × 7 ÷ 120 = 0.9917 years, about 362.2 days. The Moon pratyantardasha inside it is 10/120 of that antardasha — about 30.2 days.

One detail matters for the first mahadasha of life: its antardashas that had already finished before birth are not part of the native's life, so the table can show fewer than nine for it. The ones that remain keep their true lengths rather than being stretched to fill the balance.

Birth Time and Dasha Accuracy

Every dasha date is fixed by the Moon's degree at the moment of birth. In this chart the Moon was moving 11.89° a day, 0.496° an hour. A nakshatra is 13°20′ wide, so one hour of birth-time error changes the balance of the first mahadasha (Jupiter, 16 years) by about 217 days — and every later date moves by the same amount, because the periods after the first all run at full length.

Why Dasha Dates Differ Between Calculators

Ayanamsa. The Moon's sidereal degree depends on the ayanamsa. This page uses Lahiri (Chitrapaksha), the one most widely used in India. Another ayanamsa moves the Moon by some arc-minutes and the dates by some days.

Length of a dasha year. A dasha year here is 365.25 days. Some calculators use a 360-day savana year and some simply count birthdays. The convention is genuinely disputed. A 360-day year runs 5.25 days a year ahead, which adds up to about ten months over 60 years.

Historical time zones. This page applies the clock offset the birth place actually kept on that date. From 1942 to 1945, for example, India's clocks were six and a half hours ahead of UTC, not five and a half. A calculator that assumes +5:30 for every date moves a birth in those years by an hour — and, as the table above shows, an hour can move dasha dates by months.

The birth time itself. Usually the largest cause. A hospital record, a family's memory and a rectified time often differ by half an hour.

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