Shadbala is the classical six-fold measure of a planet's strength: Sthana, Dig, Kala, Cheshta, Naisargika and Drik Bala, each computed in virupas and totalled in rupas, where one rupa is sixty virupas. This calculator returns all six components for each of the seven planets in your chart and sets every total beside the minimum the Brihat Parashara Hora Shastra requires of that planet.
Each planet earns strength from six independent sources. Their sub-strengths are calculated in Virupas and added together to give that planet's total Shadbala.
The six are independent of one another, which is the point of the scheme: a planet weak by sign can still be strong by direction or by time of birth, and the total is what decides. Every component is computed in virupas and only the sum is converted to rupas, so nothing is rounded away in the middle of the calculation.
The six balas are summed into a total measured in Rupas, where 1 Rupa equals 60 Virupas. A planet is judged strong when its total meets or exceeds the minimum laid down in the Brihat Parashara Hora Shastra.
The threshold is a floor, not a mark out of ten. Because the minimums differ by planet, two totals are not comparable until each is read against its own requirement: Mercury has to reach 7.0 rupas and Saturn only 5.0, so a Saturn on 6.0 has cleared its bar while a Mercury on 6.0 has not.
The scheme is that of the Brihat Parashara Hora Shastra ch. 27, numbered ch. 69 in some printed editions, and the required minimums are quoted there in virupas: Sun 390, Moon 360, Mars 300, Mercury 420, Jupiter 390, Venus 330 and Saturn 300. Divided by sixty, those are the 6.5, 6.0, 5.0, 7.0, 6.5, 5.5 and 5.0 rupas shown beside each planet's total.
Several components need the time and place of birth and not merely the chart. Nathonnata and Tribhaga Bala are measured from sunrise and sunset, Hora Bala needs the planetary hour, Dig Bala is the arc from the cardinal point at which a planet is powerless divided by three, and Cheshta Bala for the five star planets is taken from the cheshta-kendra of BPHS 27.24-25. The engine's output was checked against the worked examples in B.V. Raman's Graha and Bhava Balas before it was allowed to ship.
Each planet has its own minimum in Rupas - Mercury 7.0, Sun and Jupiter 6.5, Moon 6.0, Venus 5.5, and Mars and Saturn 5.0. A total at or above that threshold is considered strong.
A Rupa is the unit Shadbala is measured in, equal to 60 Virupas. The six component strengths are each computed in Virupas, added together, and then expressed in Rupas.
Cheshta (motional) Bala applies to the five star planets - Mars, Mercury, Jupiter, Venus and Saturn - from their speed and retrogression. The Sun and Moon are given Ayana and Paksha Bala instead.
A rupa is sixty virupas. Every one of the six balas is computed in virupas, which is the unit the classical formulas use, and the six are added before the total is divided by sixty and displayed in rupas. Converting earlier would round precision away in the middle of the sum, so the conversion is left to the end.
Chapter 27, which is numbered chapter 69 in some printed editions. The required minimums are stated there in virupas: Sun 390, Moon 360, Mars 300, Mercury 420, Jupiter 390, Venus 330 and Saturn 300, which are 6.5, 6.0, 5.0, 7.0, 6.5, 5.5 and 5.0 rupas.
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For educational purposes. Astrological interpretations are traditional and not a substitute for professional advice.