House Systems

A house system is a method for splitting the chart into its twelve houses. Every system starts from the same birth time and place, and most agree on the two main angles, the Ascendant and the Midheaven. What they disagree on is how to divide the space between those angles, and that changes where the house cusps fall. A planet can land in one house under one method and the next house under another. Whole Sign is the oldest and simplest. Each house is exactly one sign, with the whole rising sign forming the first house. Placidus, the most common in modern Western astrology, divides the houses by time, based on how long each degree takes to rise, which gives houses of uneven size. Equal House measures a uniform thirty degrees from the Ascendant. Koch and several others use their own geometry again. No system is the single correct one. Whole Sign and Placidus are the usual starting points, and the practical advice is to pick one that suits the tradition a person is learning and stay consistent with it.