Astrology guide
Placidus, Koch, Whole Sign: which house system should you use?
Houses describe the areas of your life, but there are several ways to divide the sky.
The twelve houses describe areas of your life: identity, money, relationships, work… But there are several ways to divide them. That's why a planet can be in the 7th house on one site and the 8th on another.
The 5 most-used systems
Placidus · 17th century
Divides the time each degree takes to rise from the horizon to the Midheaven. Most common in the West; it struggles at polar latitudes.
Koch · 20th century
A birthplace-based variant close to Placidus. Popular in German-speaking Europe.
Whole Sign · Hellenistic antiquity
Each full sign becomes one house, starting from the Ascendant's sign. A very simple traditional method.
Equal houses · Antiquity
Exactly 30° houses from the Ascendant. A method that remains useful at high latitudes.
Porphyry · Antiquity
Splits each quadrant between the angles into three. Rarer today, it is a simple compromise.
The principle and the right choice
Signs depend on the date; houses depend on time and place. They start from the Ascendant and divide the local sky into twelve sectors.
There is no true system. Placidus is the modern default and a good starting point; Whole Sign appeals for its clarity. Stick to one system when comparing readings. All are calculated by engines such as Swiss Ephemeris, but an exact birth time matters more than the system.
Frequently asked questions
Why does my planet change house?
It sits near a house boundary, which each system places differently.
Do signs change too?
No, only the houses vary.
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