What is Vimshottari dasha?
The Vimshottari dasha meaning is literal (Vimshottari is "of 120"), and that is the whole idea: a cycle of 120 years shared out among the nine grahas, each holding a fixed number of years: Ketu 7, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19 and Mercury 17. Those nine spans add to 120 exactly, and they always run in that order, wrapping from Mercury back to Ketu. It is the dasha system in standard use across Indian astrology, and it is what people mean when they say a chart is "running Saturn". A dasha system answers a question the birth chart on its own cannot: not what the chart holds, but when each part of it is in office. The chart is fixed at birth; the dasha sequence is the order in which its nine tenants take their turn. Everything else on this page (the sub-periods, the dates, the balance at birth) is bookkeeping on top of those two facts.
How does my birth nakshatra decide where the dasha starts?
The zodiac is divided into 27 nakshatras of 13°20' each, and the nine dasha lords rule them in the same repeating order, three times round. Whichever nakshatra the Moon stood in at your birth, its lord takes your first mahadasha. That period did not begin at your birth: it began earlier, and you were born partway through it. The portion of the nakshatra the Moon had already crossed is exactly the portion of that mahadasha already spent, and what is left is the balance at birth. A Moon a quarter of the way through a nakshatra ruled by Venus leaves fifteen of Venus's twenty years still to run. The calculator prints that working in full (the degrees into the nakshatra, the percentage elapsed and the years remaining) because it is the single number every date below it depends on.
Why does the birth time change my dasha dates?
Because the Moon is fast. It covers roughly 13 degrees a day, or about half a degree an hour, so in one hour it crosses about four percent of a 13°20' nakshatra, and four percent of the nakshatra is four percent of the first mahadasha. If that mahadasha is Venus, twenty years long, an hour of error in the recorded birth time moves every boundary in the table by roughly ten months, and the shift is carried forward through the whole 120 years rather than washing out. Worse, the Moon crosses a nakshatra boundary in about a day: a birth near one of those boundaries can fall in a different nakshatra altogether and hand the first mahadasha to a different graha, which changes not one date but the entire sequence. A dasha table built from a rounded or remembered birth time should be read as approximate.
What is the difference between mahadasha, antardasha and pratyantardasha?
They are the same division applied three times over, each level cut in the same planetary order and the same proportions as the level above it. A period at any level below the first is its parent multiplied by the sub-lord's years and divided by 120: the only formula on this page, and it is applied twice. What changes between the levels is the scale of the question: years at the top, months in the middle, weeks at the bottom. This calculator computes all three, and most readings rest on the first two.
Mahadasha: the major period
The top level: one of the nine grahas holds office for its own fixed span, from the Sun's 6 years to Venus's 20. Nine of them in the fixed order fill the 120 years, and only the first is anchored to your birth. Every later one starts the day the previous ends, which is why mahadasha boundaries fall across the calendar with no relation to a birthday. This is the level people mean when they say a chart is running Saturn.
Antardasha: the sub-period, also called bhukti
Each mahadasha is cut into nine antardashas in the same planetary order, beginning with the mahadasha lord's own. Each is sized as the parent period multiplied by the sub-lord's years and divided by 120, so Venus inside a Venus mahadasha runs 20 × 20 ÷ 120, three years and four months, while the Sun inside that same mahadasha runs exactly one year. The mahadasha and antardasha pair is what most readings actually work from.
Pratyantardasha: the third division
Dividing an antardasha by the same rule gives the pratyantardasha: nine again, in the same order and the same proportions, usually running from a few weeks to a few months. The tradition uses this level to narrow a reading already made higher up rather than to make one. A period this short is also far more sensitive to an inexact birth time than the mahadasha above it, since the same error moves a much smaller span.
What does this Vimshottari dasha chart show?
The Vimshottari dasha table above carries four things, in the order you need them. First, the mahadasha running today, with the antardasha and pratyantardasha inside it and the date each one ends. Second, the full table of nine mahadashas with start and end dates, the current period marked and the finished ones dimmed, so the whole 120-year cycle is visible at once. Third, the nine antardashas of the running mahadasha, dated the same way. Fourth, the balance at birth with its arithmetic shown: which nakshatra, how many degrees into it, what fraction of the first period that came to. Each mahadasha also carries a short note on the character the tradition gives that graha's period, kept visibly separate from the dates so it is never mistaken for something the engine computed.
What can a dasha tell you, and what can it not?
A dasha is a clock, not a prophecy. It says which graha is in office and for how long; it does not say what happens, and no careful reading turns a period into a named event. What the tradition does with it is narrower and more useful: a period is read through the condition of its lord in your own chart (how strong it is, which houses it rules and occupies, what aspects it), so the same Saturn mahadasha is read one way where Saturn is dignified and another where it is not. Classical texts describe the character of each graha's period in broad terms, and those descriptions are traditions of reading, attributed as such on the results page. Nothing here is a statement about health, lifespan or any specific outcome, and no date on the table should be treated as one.
Why do two sites give different Vimshottari dasha dates?
Two settings account for nearly every disagreement, and neither of them is a mistake; publishing dates without naming the convention is. The first fixes where the sidereal zodiac begins, and so where in its nakshatra the Moon falls; the second fixes how long a dasha year is. They compound rather than cancel. A shifted balance at birth moves every boundary by the same amount, while a different year length stretches or shrinks each of the nine spans in turn, so two tables drift further apart the further down them you read.
The ayanamsha, which fixes the Moon's longitude
The ayanamsha is the offset between the tropical and the sidereal (nirayana) zodiac, and it decides where in its nakshatra your Moon falls. We use Lahiri (Chitrapaksha). A site on a different one places the Moon a fraction of a degree away, which moves the balance at birth and every date after it, and for a Moon near a nakshatra boundary it can hand the first mahadasha to a different graha altogether, which changes the whole sequence rather than one date.
The length of a dasha year
We use 365.2425 days, the mean length of a calendar year. Some implementations use a 360-day savana year instead, which shortens the whole cycle by about 629 days: by the end of the 120 years the two tables stand nearly two years apart, though both started from the same Moon and the same nakshatra. Neither convention is wrong, and a table that does not say which it used cannot honestly be compared with another.
How is a dasha read alongside the rest of the chart?
Timing on its own is half an answer, and the tradition never uses it alone. The first thing a reader checks is the strength of the dasha lord: a graha short of its own Shadbala minimum is read as constrained in what it can carry out, whatever period it is running, which makes our Shadbala calculator the natural companion to this table. The second is what that graha rules and where it sits, which is on your full birth chart. The third is the current transits, read from the natal Moon and weighed against Ashtakavarga bindus for the sign being crossed. A yoga is generally said to express itself during the periods of the grahas that form it, which is why the yoga calculator and this one are read together.
How this is calculated
Nirayana rashis with the Lahiri (Chitrapaksha) ayanamsha and whole-sign bhavas, computed to arc-second accuracy. Sunrise and sunset are the ones almanacs show, the Sun's upper edge with refraction, so the daily windows agree with the calendars you compare them with. More on our method.