What is Shadbala?
Shad means six and bala means strength. Shadbala, described in the Brihat Parashara Hora Shastra, measures the strength of the seven planets from the Sun to Saturn as the sum of six components. A planet can sit in a good sign and still be weak overall, or in a poor sign and be strong for other reasons, which is what the combined figure is for.
Strength is measured in shashtiamsas, sixtieths, and sixty shashtiamsas make one rupa. A planet whose total reaches its required minimum is considered able to give the results of its house and dasha; below the minimum it is considered weak.
The six components
Sthana Bala is positional strength: exaltation, own sign, friendly signs and divisional placement. Dig Bala is directional strength, since each planet is strongest in one house. Kala Bala is temporal strength, from the time of day, the month, the year and the weekday. Chesta Bala is motional strength, mainly from retrogression and speed. Naisargika Bala is natural strength, fixed for each planet. Drik Bala is aspectual strength, from the benefic and malefic aspects the planet receives.
How to read the result
Compare each planet’s total in rupas with the minimum shown beside it. A strength percentage above 100 means the planet meets its requirement. A planet that is weak in Shadbala but is the lord of your current mahadasha is worth attention, because a weak dasha lord tends to deliver less of what its placement promises.
Shadbala covers the seven visible planets only. Rahu and Ketu are not measured. Different traditions use slightly different minimum values and method details, so treat the figures as one input to a reading, not a verdict.