House systems: Placidus, whole sign, and equal houses
The twelve houses divide the ecliptic into twelve areas of life. Cusps follow the house system. At the same instant, a different house system can change the houses. Planet longitudes stay.
Editorial review: 2026-09-22 · Reviewed by fateshow · Editorial method
Three house systems cut differently
Placidus trisects time, so cusps can be unequal. Whole sign takes the whole rising sign as the 1st house, 30° each. Equal houses step 30° from the Ascendant.
Placidus is printed first. Write the system’s name before switching.
Houses can change while longitudes stay
A planet’s longitude comes from the ephemeris. The house system only decides which house that longitude falls in.
Under Placidus here, the Sun is in the 9th and the Moon in the 7th. Whole sign recalculates the houses. It does not change Taurus or Pisces.
No clock means no cusps
Cusps depend on the Ascendant. Without a birth time or place, the twelve houses stop. Signs can remain.
Do not invent a time to fill the twelve houses.
Illustration: Sun and Moon under Placidus
The same birth. Placidus. Sun in Taurus in the 9th, Moon in Pisces in the 7th. Those houses belong to this system. They are not the only cut.
The definition is on What Western astrology is.
Common mistakes
- Saying the longitude changed because the house system changed.
- Comparing houses without naming the system.
- Filling twelve houses without a birth time.
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Frequently asked questions
Which system is the default?
Placidus. Whole sign and equal houses have to be named separately.
Can a house-system change move the Sun out of Taurus?
No. Taurus is the sign of the longitude. The house system only changes the house.
Is Vedic whole sign the same chart as whole sign here?
No. Vedic subtracts an ayanamsa first, then uses whole sign. This zodiac is tropical.
Sources and editorial basis
- 1. House-system notes
Placidus is the default. Whole sign and equal houses can be computed separately, and the choice is stored on the chart.
- 2. fateshow rule snapshot
Supports only the fields printed in the illustration.