Dasha and Antardasha System is an integral part of Indian Astrology. Maharishi Parashar has described 30 types of conditions in Hora Shastra. There are several types of dashas described in the Gemini system. But according to Maha Rishi Parashara.
" दशाबहुविधास्तासु मुख्या विंशॊत्तरी मता"
( There are many types of Dashas, but the main one is Vimshottari Dasha.)
120 years is considered to be the complete age in Kali Yuga. Vimshottari is the main dasha in all dashas. Astrologers of India mainly use this dasha for this reason. Vimsootri dasha used to know the period of the events happening in life. It's calculated from the constellation of the Moon at the time of birth. In astrology, there are nine planets, and there are 27 constellations, and 27 constellations are distributed among nine planets. Dasha year is fixed for each planet. Anterdasha, Pratyanter Dasha, and shooksham Dasha are parts of Vimsootri Dasha. When an event will happen in a person's life, it is seen from Vimshottari Dasha but if one wants to know the time of the event objectively, then Antardasha, Pratyantar Dasha, and Shooksham Dasha are used.
Nakshatra Lord/Planet Dasha Varsh/Periods
Ashwani - Magha - Moola Ketu 7 Year
Bharini - Poorva Phalguni - Poorva Ashada Shukra/Venus 20 Year
Kritika - Uttra Phalguni - Uttra Ashada Surya/Sun 6 Year
Rohini - Hasta - Shravan Chanderma/ Moon 10 Year
Mrigshira - Chitra - Dhanishtha Mangal/Mars 7 Years
Adra - Swati - Shatbhisha Rahu 18 Year
Poonervasu - Vishakha - Poorva Bhadrapada Guru/Jupiter 16 Year
Pushya - Anuradha - Uttra Bhadrapada Shani/Saturn 19 Year
Ashlesha- Jayeshtha - Revti Budh/Mercury 17 Year
The sum of the dasha years of all the planets is 120 years. The order of the dashas will remain the same as written above. The dasha of the planet related to the constellation in which the Moon will be at the time of birth will be the dasha at the time of birth. The part of the constellation that has passed is the BHOOKT dasha and whatever it is from is the BHOGYA dasha. In today's time, dasha can be generated with precision using astrology software. After calculating Dasha what is more important is how to do predictions using Dasha.