How Vimshottari dasha works
Vimshottari is the most widely used dasha, or planetary period, system. It covers a cycle of 120 years shared among nine planets, each ruling a fixed span: Ketu 7 years, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19 and Mercury 17.
Your sequence begins with the lord of your birth nakshatra. How far the Moon had already travelled through that nakshatra decides how much of the first period was over at birth; what is left is called the balance of dasha. The periods then follow in the order above.
Mahadasha, antardasha and pratyantardasha
Each mahadasha (major period) is divided into nine antardashas (sub-periods), starting with the mahadasha lord itself and following the same order. An antardasha's length is proportional: the mahadasha's years multiplied by the sub-lord's years, divided by 120. Jupiter–Saturn, for example, lasts 16 × 19 ÷ 120 = 2.53 years, about two and a half years. Each antardasha is divided again into pratyantardashas in the same way.
Yogini dasha
The calculator also gives the Yogini dasha, a shorter 36-year cycle of eight yoginis (Mangala, Pingala, Dhanya, Bhramari, Bhadrika, Ulka, Siddha and Sankata) lasting from one to eight years each. Many astrologers use it to cross-check timing from Vimshottari.
Reading your periods
A dasha shows which planet's themes are emphasised during a stretch of life, judged by that planet's sign, house, strength and lordships in your own chart. It is not a fixed fate. The Sade Sati dates and your full Janam Kundli add the transit picture.
Frequently asked questions
How accurate are the dasha dates?
As accurate as the birth time. The Moon crosses a nakshatra in about a day, so each hour of error in the birth time can move the dates by several months.
How do I see which dasha is running now?
The report marks the mahadasha, antardasha and pratyantardasha running today.
Is a Saturn or Rahu mahadasha always difficult?
No. A well-placed Saturn or Rahu can bring some of the most productive years of a life. The results depend on the planet's condition in your chart.