Shadbal refers to the six types of strengths a planet possesses. It helps in computing the actual power a planet possesses. These strengths are computed for the seven Grahas or planets from Surya (Sun) to Shani (Saturn). Rahu and Ketu are not considered. Shadbal mainly helps in analyzing how well a particular mahadasha or antardasha will go for a person.
Shadbal consists of the following six bals (strengths) along with their subdivisions:
1. Sthaan Bal (positional)
(a) Uchch Bal (exaltation)
(b) Saptvargiya Bal (strength accruing out of positions in Rasi, Hora, Dreshkan, Saptans, Navans, Dvadashans and Trishans kundli/horoscope)
(c ) Yugmayug Bal (acquired by placement in odd, or even Rasi and in odd, or even Navmansh-D9)
(d) Kendra Bal (due to placement in centre-1,4,7,10 or Panaphara-2,5,8,11 or opoklim-3,6,9,12 house)
(e) Dreshakan Bal (due to placement in first, second, or third decanate of a Rashi/sign)
2. Dig Bal or Disha ka Bal (directional)
3. Kaal Bal or Samay ka Bal (temporal or time)
(a) Natonnat Bal or Diva Ratri Bal (diurnal and nocturnal)
(b) Paksh Bal (fortnight)
(c ) Tribhaag Bal (due to day/night being made in 3 parts)
(d) Aabd Bal or Varsha Bal (astrological year)
(e) Maas Bal (month)
(f) Vaar Bal (weekday)
(g) Hora Bal (planetary hour)
(h) Ayan Bal (equinoctial)
(i) Yuddh Bal or Parishthiti Bal (due to partaking in war between Grahas/planets)
4. Cheshtaa Bal (motional)
5. Naisargik Bal (natural)
6. Drik Bal or Drishti Bal (aspectual)
All the above Bals or strengths are briefly described below:
1. Sthaan Bal (Positional): The strength acquired by a planet due to its position in the chart according to rashi and house is sthaan bal.
(a) Uchch Bal: The strength acquired as per the exaltation and debilitation point.
(b) Saptvargiya Bal: Strength as per position in mool trikon rashi, swarashi (own house), friend, enemy or neutral rashis in all the 7 divisional occupations viz. lagna, hora, dreshkan, saptmansh, navmansh, dashansh and trishansh.
(c) Yugmayug Bal: According to even and odd rashi positions in lagna(D1) and Navmansh(D9).
(d) Kendra Bal: As per positions in the centre houses (1,4,7,10) Panfar (2,5,8,11) or Opoklim (3,6,9,12) houses of the main chart.
(e) Dreshkan Bal: Male, female and hermaphrodite planets get power according to placements in the first, second and third decanates.
2. Dig Bal (directional): Strength acquired as per the direction of the planets in the chart. 1st house-east-Mercury,Jupiter. 4th house-north-Moon,Venus. 7th house-west-Saturn. 10th house-Sun,Mars.
3. Kaal Bal (temporal): It refers to strength acquired by planets due to a particular time.
(a) Natonnat Bal: Sun, Jupiter and Venus possess full power at midday, Moon, Saturn, and Mars at midnight while Mercury is powerful all day long.
(b) Paksh Bal: According to the fortnight in which a person is born. Sun, Mars, Saturn, weak Moon and Malefic Mercury are powerful in krishna paksh (decreasing moon) while Venus, Jupiter, Strong Moon and benefic Mercury are powerful in Shukla Paksh (increasing moon).
(c) Tribhag Bal: Depends on the birth time which falls in any 3 parts of the day and night. Jupiter gets full power at all times.
(d) Varsha Bal: According to the lord of the day on which the astrological year of birth starts.
(e) Maas Bal: According to the lord of the day on which the astrological month of birth starts.
(f) Vaar Bal: According to the lord of the day of birth.
(g) Hora Bal: Hora means planetary hour. Each day from sunrise to sunrise is divided into 24 equal parts of one hour. According to the planet which rules the birth hora. Horas are to be calculated for mean local time and not standard time of births.
(h) Ayan Bal: According to the equatorial positions and the angular distance from equator and the orbit.
(i) Yuddh Bal: Should there be a war between the starry planets, the difference between the Shad Balas of the two should be added to the victor’s Shad Bal and deducted from the Shad Bal of the vanquished.
4. Chestaa Bal (motional): Eight kinds of motions are attributed to the planets. These are Vakri (retrogression), Anuvakr (entering the previous Rasi in retrograde motion), Vikal (devoid of motion), Mand (somewhat slower motion than usual), Mandatar (slower than the previous), Sama (somewhat increasing in motion), Char (faster than Sama) and Atichar (entering next Rasi in accelerated motion). The strengths, allotted due to such 8 motions are 60, 30, 15, 30, 15, 7.5, 45 and 30.
5. Naisargik Bal (natural): This strength is calculated according to a planet’s light reaching the earth. It is fixed and same for all charts. The natural power in decreasing order is Sun, Moon, Venus, Jupiter, Mercury, Mars and Saturn.
6. Drik Bal (aspectual): The power acquired by planets due to being aspected by other planets which are behind them. The aspectual strength is maximum when planets are at 180 degree from each other. Mars, Jupiter and Saturn also have special aspectual powers. Reduce one fourth of the Drishti Pinda, if a planet receives malefic aspect and add a fourth, if it receives a Drishti from a benefic.
Apart from these six types of strengths there are also Bhav Bal (House), Rashmi Bal (Light), Isht and Kasht Bals.