Astrology Basics

Selecting A House System

by Joelle Steele

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Western astrology divides the natal chart into twelve sections called "houses," which indicate the different areas of interest and activity in your life. How those houses are calculated depends on the house system used. Which system you select is a matter of personal choice; no system is "right" or "wrong." There are at least eight major house systems in use throughout the world, but the three most commonly used in the United States are Placidus, Koch (pronounced "coke"), and Equal, respectively. Among the many other house systems are Alcabitius, Campanus, Meridian, Porphyry, and Regiomontanus.

As you can see by this comparison chart, this person's house cusps and planet placements vary from one house system to another:

House Systems Comparison Chart


Two of the three most popular houses systems, Placidus and Koch are "unequal" house systems. These can result in "interceptions," which occurs when two opposite signs of the zodiac are on the cusps of two houses, while two other opposite signs are not on any house cusps at all and are instead inside of houses with neighboring signs on their cusps. The signs intercepted by Koch are not necessarily the same ones that would be intercepted using Placidus. Interceptions occur more frequently for birth place latitudes the closer they are to the polar regions. Placidus and Koch charts always result in the Midheaven being the cusp of the 10th house.

The Placidian system is named after its 17th century inventor, an Italian monk named Placidus de Titus. It is used by at least 80% of astrologers in the U.S. because it is the most widely known system and its house tables are readily available in most areas. The Koch system is the second most commonly used house system in the U.S. It originated in Germany and is named for its first publisher, Dr. Walter Koch.


Another of the three most popular house systems is Equal housesm which is just what its name implies. All the houses have the same degree on each cusp, and there are no interceptions. Equal house systems are especially useful for people born in the northernmost and southernmost latitudes, and this system is the most popular one in use outside of the United States.


This house system dates to the Greeks in the 1st century AD. It is an unequal house system and the houses can vary in size significantly, but it does not result in problems with interceptions in the polar regions.


This house system may have been created by 15th century brothers Joseph and Matthew Campanus, although some believe it dates back to the 13th century. Regiomontanus is named for a 14th century German astronomer. These systems are virtually identical, and like other unequal house systems, both of these systems result in interceptions with birthplaces the closer they are to the polar regions.


This house system is used most often by astrologers who practice Uranian astrology. The Midheaven is the cusp of the 10th house, but the Ascendant is the East Point (Equatorial Ascendant).


This house system is named for the Neoplatonist, Porphyry, and is an ancient system dating to the 34d century AD. The Midheaven is the cusp of the 10th and the Ascendant the cusp of the 1st, but the rest of the houses are divided equally. Like some of the other house systems, there are severe interceptions the closer the birthplace is to a polar region.

No given house system is better than another, only different. Astrologers select the systems which they feel work best for them and for their clients. They also select systems which best suit the kinds of astrology they practice. For example, those who practice astropsychology are often inclined to use Placidus, and those who practice Uranian astrology are more likely to select Koch. If you are unsure which system is best for you, try both, or try one of the other house systems, and see which produces the most reliable results. That's the best house system — for you.

This article last updated: 12/19/2014.