The period of Sade-sati starts when Saturn enters the zodiac sign immediately before the zodiac sign of Moon at the time of the birth of the individual. That is, if the Moon sign (Ayamsha) at the time of birth of the native was Taurus, then the Sadesati will begin when Saturn enters sign Aries. The Sadesati will continue while Saturn transits over this sign and the next two signs, i.e. the birth sign and the sign after it. Saturn spends around 2½ years in each sign. To cross these three signs it takes about 7½ years. Thus the name Sadesati which literally means seven and a half.

The period of Sade-sati starts when Saturn enters the zodiac sign immediately before the zodiac sign of Moon at the time of the birth of the individual. That is, if the Moon sign (Ayamsha) at the time of birth of the native was Taurus, then the Sadesati will begin when Saturn enters sign Aries. The Sadesati will continue while Saturn transits over this sign and the next two signs, i.e. the birth sign and the sign after it. Saturn spends around 2½ years in each sign. To cross these three signs it takes about 7½ years. Thus the name Sadesati which literally means seven and a half. 

Saturn Mahadasa (especially the first three years of Saturn antardasa within this mahadasa) has intense saturnine effect on the individual and influences the individual much more than the Sade Sati period. Again, those born, say between 1965-1968 and natal moon in either of Rohini, Hasta or Shravana nakshatra are undergoing Shani antardasa in Shani Mahadasa.

According of astrology this is a troublesome time for the individual who is going through it. There may be a lot of challenges in a person's life, and he may face accidents, sudden failures, money and health problems. However, there's another of astrology that believes that though the sadesati period is challenging, it is not as damaging as many astrologers claim, and that many people actually achieve a lot of success during the period of Sadesati.