The Sanskrit term dasha means period. Vimshottari Dasha literally meaning Vimshottari Period is a concept in vedic astrology which calculates different stages of life and planet which holds maximum influence during those stage of life. Well planets do not influence your thoughts or actions to be precise. Your previous and present karma do. But planets do point to the likely events that could happen during certain stages of life. Judging vimshottari period and sub-period is an effective way to analyze what that stage of life has in-store for a particular person. Vimshottari dasha is not difficult to calculate with use of modern day astrological software. As long as birth-time is correct most of them give fairly accurate results. 

     Vimshottari Dasha system assumes a person lives for a total of 120 years. Most normal humans would be covered in one hundred twenty years lifespan so its fairly accurate. Vimshottari Dasha system allocates certain years of life to a planet to carry out its influence. For example Saturn period of vimshottari dasha runs for around 19 Years. During those times the effects of Saturn reign supreme on the life of a native. Saturn is the planet which deals with karma and its fruits. So expect good results during Saturn period if previous karma was good. If you have difficulties during Saturn period then do acknowledge that you are getting fruits of your previous bad karmas.

     Below table shows the Planet and Periods allocated to them. Judging these times and its associated possible events can become a key to being successful in life but its necessary not to over rely on these times. For example Vimshottari Period/Sub-period of Venus or Seventh House lord would suggest chances of marriage.Those who wish to marry and settle down should do so during those periods for better chances of success.

     This concept can be quite confusing but its actually quite simple. Dasha means period while antardasha means sub-period. Dasha Period suggests times when the effects of concerned planet are maximum on an individual. But antardasha or sub-period suggests likely events which may happen in life of the native more accurately. Think of dasha period as type of food. For example Italian, Indian, Continental or Chinese. Then antardasha period are different recipes in those type of food. For example Thai Curry, Italian Pasta, Indian Rice Pudding or Chinese Noodles. Important point to note is Antardasha has to have dasha period in front of it. Cause there can be Indian Curry as well as Thai Curry. There can be Italian Spaghetti and Chinese Noodles which look similar but taste are totally different. Similarly there can be Saturn Dasha and Mercury Antardasha which could provide different results from Jupiter Dasha and Mercury Antardasha. If an individual has Jupiter Dasha and Mercury Antardasha running then native could see progress in education sphere cause both the planets are associated with knowledge(Jupiter) and general knowledge(Mercury). If Jupiter or Mercury also happen to be associated with fourth house or fifth house then it is all the more likely that there is success in education sphere with little effort. But Saturn is a task master and his main period would ensure native needs to work very hard to see success in any work.

     One just needs to know the Dasha/Period and Antardasha/Sub-Period and the associated portfolios to decipher more how that stage of life would turn out.

     There are few ways suggested to judge effects of dasha and antardashas. But its better to keep it sweet and simple. Simplest way is to judge the nature of planets and associated portfolios. For planets like Saturn, Rahu, Jupiter or Ketu one can also check the current transit via horoscope house. If current transit is bad than chances are that period of life would be bad.     

     When you judge dasha periods there is no thumbrule or golden print to say if that phase of life would be good or bad. Planets only enforce the mandate of karma on you. As long as you have done good karma no bad period could do you major harm. There would always be periods and sub-periods which would favor or be unfavorable for certain things and situations. Even a favorable dasha periods can only give fruits if you have done the desired karma. Otherwise they pass without giving any favorable effects.