House System

A house system is a method for calculating the 12 houses in a birth chart. Houses represent different areas of life, such as identity, money, communication, home, relationships, and career. The cusp (starting point) of each house depends on the system used, which can shift planets between houses and change interpretations.

How it works

All house systems use the Ascendant (rising sign) as the cusp of the 1st house and the Midheaven (MC) as the cusp of the 10th house. They differ in how they divide the space between these points. Common systems include:

• Placidus: The most popular system, based on time-based divisions. It works well for most latitudes but can produce distorted houses near the poles.
• Whole Sign: The oldest system, where each house equals one zodiac sign starting from the rising sign. Simple and consistent, it ignores the actual degree of the Ascendant for house boundaries.
• Koch: Similar to Placidus but uses a different calculation. Popular in some European traditions.
• Equal House: Divides the ecliptic into 12 equal 30° segments starting from the Ascendant. Simple but can place the MC in a non-10th house.
• Regiomontanus: Uses the celestial equator for division. Historically used before Placidus.

In practice

When reading your chart, the house system affects which planets fall into which houses. For example, if your Ascendant is at 5° Leo, in Placidus the 2nd house might start at 2° Virgo, while in Whole Sign the 2nd house starts at 0° Virgo. A planet at 1° Virgo would be in the 2nd house in Placidus but the 1st house in Whole Sign. There is no "right" system — astrologers choose based on tradition or personal preference. Astraly uses Placidus by default, but you can switch to Whole Sign in the chart settings.

Explore your own chart and see how houses shape your life by building your chart on Astraly.