Arudha = projection of reality. If the 7th house (marriage) is in Taurus and its lord (Venus) is in Libra, the Arudha of the 7th (Dara Pada) is calculated by the distance 7th → Venus (6 houses), projected forward from Venus (6 houses forward from Libra = Taurus). Dara Pada = Taurus.
General formula: Measure house cusp → lord's house (distance D). Count D forward from lord's house to find the arudha sign.
Exceptions (Swasthe Arudha, "exception arudhas"):
Lord in 1st from house: Arudha = 10th from house.
Lord in 7th from house: Arudha = 4th from house.
Example: 7th lord in the 1st house (7th itself, if lord is in the 7th) → Arudha = 10th from 7th = 4th house. This is why powerful upapadas often fall in the 4th; it indicates spouse or partnership gains grounded in property and family.
Arudhas are computed for all 12 houses (plus Upapada Lagna from the 12th). Arudha Lagna (AL, from the 1st) = perceived public image. Upapada Lagna (UL, from the 12th) = spouse's family and marriage circumstances.
The calculator computes all 12 arudhas. You will interpret AL placement, UL placement, and the status of karaka planets relative to them.