In short
House systems divide the same chart in different ways. This comparison shows how four common systems define cusps and why a planet can change houses without changing signs.
Four common house systems
| System | How it divides the chart | Key consequence |
|---|---|---|
| Whole Sign | The entire rising sign is House 1, and each following sign becomes the next house. | Every house starts at 0 degrees of a sign. |
| Equal House | House 1 begins at the exact Ascendant degree, then every cusp advances exactly 30 degrees. | Houses are equal, but signs can be split across them. |
| Placidus | A time-based quadrant method divides the arcs between chart angles into three parts. | House sizes vary and calculations can fail at extreme latitudes. |
| Porphyry | Each ecliptic arc between the four chart angles is divided into three equal sections. | House sizes vary, using a simpler quadrant division. |
The birth chart calculator uses Whole Sign houses and labels that choice in every result.
How to compare four house systems
What changes when the cusp method changes
Changing house systems does not move a planet or alter its zodiac sign. It changes the boundaries used to assign that placement to an area of life.
Pick one system before interpreting houses, record it with the chart, and use it consistently. Read the twelve-house reference for the life area associated with each house.
A different system does not move a planet
Calculated positions are astronomical data. Astrological meanings are a symbolic tradition, not scientific predictions or professional advice.