Every degree of the zodiac is governed by a hierarchy of three lords:
Sign Lord (weakest): The classical ruler of the sign. Sun rules Leo; Mercury rules Virgo. The sign lord provides general flavor but not the determining factor.
Star Lord / Nakshatra Lord (middle): The 27 nakshatras are ruled by planets in Vimshottari order (Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury). If a planet is in Ashwini nakshatra (1st), Ketu is the star lord. Star lord influences the outcome more than sign lord.
Sub-Lord (strongest / FINAL AUTHORITY): Each nakshatra is divided into 9 unequal sub-periods using Vimshottari dasha year ratios (7, 20, 6, 10, 7, 18, 16, 19, 17 = 120 years). The 9 sub-lords are Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn, Mercury, in sequence. The sub-lord is the final determinant of outcome.
Example: Planet at 15°44' in Virgo: Virgo is ruled by Mercury (sign lord). The degree falls in Hasta nakshatra (star lord Moon). Hasta is divided into 9 parts; 15°44' falls in the 6th part, ruled by Rahu (sub-lord). In KP reading, Rahu is the effective ruler, not Mercury or Moon.
Key principle: If sub-lord is benefic for the question (e.g., for a 7th house query, if sub-lord is Venus or Jupiter), outcome is YES. If sub-lord is malefic (Saturn, Mars, Rahu), outcome is NO or DELAYED. Sign lord and star lord provide context but do not override sub-lord verdict.
The calculator resolves sign-star-sub hierarchy for any degree. You will practice identifying sub-lords for key planets and house cusps and apply the hierarchy to predict outcomes.
Working the hierarchy by hand. Take a planet's sidereal longitude. The sign gives the sign lord. Divide the zodiac into 27 nakshatras of 13 degrees 20 minutes each to find the nakshatra and its lord. Then divide that nakshatra into nine parts in the Vimshottari proportions to find the sub. Doing this manually two or three times fixes the structure far better than reading about it.
Why the subs are unequal. The nine subs follow the dasha year ratios: Ketu 7, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19, Mercury 17, totalling 120. A Venus sub is therefore more than three times the width of a Sun sub. Students who assume nine equal subs of 1 degree 29 minutes each will misassign most planets.
The interpretive logic. The three levels are often described as proposer, supporter and decider. The sign lord sets the general field, the star lord supplies the energy and the flavour of the result, and the sub-lord decides whether the matter proceeds. When the sub-lord signifies houses hostile to the question, the answer is no regardless of how favourable the sign and star lords appear.
A worked check. A planet at 15 degrees 44 minutes of Virgo sits in Hasta, whose lord is the Moon, and falls in the Rahu sub. In KP the effective ruler is Rahu, not Mercury and not the Moon. If your reading of this planet begins with Mercury's dignity, you are still reading classically, not in KP.