Pratyantardasha
A pratyantardasha is the third level of the Vimshottari dasha: a short sub-sub-period inside each antardasha, lasting from a few days to under seven months, used to narrow down timing.
Also known as: Pratyantar dasha, Pratyantardasa, Pratyantar, sub-sub-period, third-level dasha, PD dasha
Each antardasha is divided again into nine pratyantardashas, in the same planetary order and the same proportions. The sequence starts with the antardasha lord. So within Saturn–Mercury, the first pratyantardasha is Mercury’s, followed by Ketu’s, Venus’s and the rest.
The length is the antardasha’s length multiplied by the planet’s years and divided by 120. The shortest, Sun–Sun–Sun, lasts about five and a half days; the longest, Venus–Venus–Venus, a little over six and a half months.
Astrologers use pratyantardashas to pick out the likely months for something the mahadasha and antardasha already promise, such as a move or a wedding. On their own they promise nothing. They only refine what the larger periods and transits indicate.
Because these periods are short, small errors matter. A birth time that is out by 15 minutes can shift every date by weeks, so treat exact dates as approximate unless your birth time was well recorded. Below this level come the sookshma and prana dashas, used mainly by specialists.