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House Systems: Dividing the Sky

I recently asked my readers to send me their questions about astrology – what confuses them? What would they like to know more about? Nearly every response was about house systems. Why are there so many of them? Which one is best? Which one am I using, and why?

What are houses?

First, an explanation of what they are in the first place. An astrology chart is a symbolic representation of the sky at the time of your birth. It contains glyphs representing each of the planets (plus the Sun and Moon) placed in a wheel with twelve sections, which are called houses. The lines separating the houses are called house cusps.

So far, so good. Look up into the sky and you can see the Sun, Moon, and most of the planets an astrologer uses in your birth chart. But do you see any little lines, separating the sky into 12 pie slices, or “houses” like the ones you see on a birth chart? Hopefully not. If you do, fine-tune your reception.

It’s helpful, though, this concept of interpreting a planet based on its place in the sky at a particular moment, and which planet has dominion over a piece of the sky. So astrologers use a variety of “house systems,” or methods of dividing up the sky into twelve sections. How this is done is a critical question, because the method of splitting up the houses can determine the house placement of the planets. Each house has a particular vibe, focus, and landscape. For instance, in once house system you might find your Moon in the 8th house – a soulful, mysterious, sometimes brooding placement – while in another it appears in the more optimistic and gregarious 9th house. How can both be true?

If you ever find yourself among a group of astrologers and the conversation lags, introduce the subject of house systems and watch the fur fly! A lot of us have strong opinions about which is the best and why. What follows is a brief (believe it or not) summary of house systems – the ones that are popular, how they’re different, and why you should care.

Should you care about house systems?

I‘m going to level with you: If you are a casual astrology hobbyist, the answer is probably “no.” (Also, if you don’t have an accurate birth time, the whole question of houses is moot – because the most popular house systems are derived from the Ascendant point, which changes about every four minutes. If your birth time is unknown, the Ascendant, and therefore the houses, can’t be accurately calculated. In that case, just use Solar or Whole Sign Houses at sunrise.)

But if your birth chart has planets that fall close to a house cusp, the question of house system becomes more pressing. If you’ve calculated your birth chart at and are used to seeing your Venus in the festive 5th house and then someone else’s chart for you – calculated in a different system – places it in the more home-loving 4th house, you may feel disappointed. I’ll be honest: In cases like these, one often chooses the house system that gives them the chart they like best. For instance, my Placidus chart has Venus in the 7th house, but I simply relate better to my Koch chart’s 8th house Venus. I’m not saying this is the best approach to this dilemma, but it’s probably the most human.

If you were born above 66 N latitude or below 66 S latitude, your chart will “break” certain house systems. Either all the planets will fall in just a couple of houses, or the computer will default to an equal house system. I’m not going to go into why. But if you were born outside 66N and 66 S latitudes, consider just using Whole Sign houses or Equal Houses.

House systems in action

A good explanation of different house systems and their theoretical and mathematical underpinnings can be found here. For many astrologers, though, house systems tend to be a matter of habit. Often, we pick one up from our teachers or the current popular trends and just stick with it, more or less unquestioningly.

For instance, my default house system since 1989 has been the Koch (pronounced “coke”) house system. If you run across an astrologer who uses Koch, it’s a good bet they came of astrological age in the late 1980s, when this system was all the rage and considered a bit more “technical” than the popular Placidus (pronounced “PLA-si-dus” – pla rhymes with “at”) system. Alternately, twenty years from now it will probably be another house system that’s in vogue, and all the early 21st century astrologers will be recognized by their use of Whole Sign houses.

Popular Systems and How They’re Different

Equal Sized Houses Some house systems split the wheel into 12 equal sections of 30 degrees. Plus side: Elegantly simple, and no intercepted signs. Down side: Midheaven degree (normally the cusp of the 10th house) can move around to different houses, which can be disconcerting.

Whole Sign houses begins the first house cusp with 0 degrees of the Ascendant sign, the second house cusp with 0 degrees of the following sign, and so on. It’s the go-to system for Hellenistic astrologers and currently very popular, especially among younger astrologers. It ensures consistent planetary rulership of the houses (no pesky interceptions), which is particularly critical in certain forms of predictive astrology, such as horary or electional.

The Equal House system is similar, except it takes the degree and sign of the Ascendant and uses that degree of the next sign on the 2nd house cusp, and so forth. So if 12 degrees and 37 minutes of Leo are rising, the next house as 12.37 Virgo, the next 12.37 Libra, and so on. This system accentuates the importance of the Ascendant, which is arguably the most personal house cusp. It’s a bit of an “all about me” chart.  If you don’t have an accurate birth time, you can use Solar Houses, which is basically equal houses with the Sun’s degree at sunrise on each of the house cusps.

Unequal (quadrant-based) houses

In these systems, houses usually vary in size, sometimes dramatically. Therefore, planets can fall in different houses depending on what house system is used to calculate your chart. These systems can also result in intercepted signs. For instance, you may have the same sign on two houses in a row, then skip a sign. The sign didn’t go away – all 30 degrees of it are in a house – but it doesn’t show up on a house cusp. It has to get its work done more subtly, behind the scenes, or through its planetary ruler. More about intercepted signs here.

The most popular of these systems are based in time – the time it takes for planets to move from the eastern horizon to the meridian, and from the meridian to the western horizon. They just vary in how they split up that time into house cusps. All agree on the Ascendant/Descendant degree and signs, and on the Midheaven/IC degree and signs. But the second/eighth, third/ninth, fifth/eleventh, and sixth/twelfth houses can be different from one system to the next.

Placidus is probably the most popular of these systems. If you’ve ever calculated your chart at and didn’t change the default house system, you’re using a Placidus chart. Placidus is an elegant system with a lot of inherent wisdom, so don’t roll your eyes at it because it seems old-fashioned. It’s a very old house system and very respectable; its house cusps correlate to the planetary hours, if you’re into that. If you want a nice, solid, pinstripes and sweater set type of house system, this one is for you. It’s a mess at extreme latitudes, though.

Koch will usually yield a very similar chart as one calculated in Placidus. Koch is an extremely modern system, with the table of houses published in the early 1970s. It will usually give a chart that’s very similar to Placidus, but the math behind it is a bit more straightforward and uses the Midheaven as its initial reference point. For this reason, the Midheaven is particularly important in this chart; you could consider playing around with it to see if it gives particular insights into career matters. Note that, in contrast to the same chart in Placidus (above), Jupiter is now in the 4th house and Saturn is in the 5th. Like Placidus, though, this one falls apart at extreme latitudes.

Porphyry (POR-fur-y) is older than dirt. The math is more complicated than whole signs or equal houses, but much simpler than Placidus. The intermediate house cusps are based on the number of degrees between the angles. For instance, an Ascendant of 12.37 Leo and IC of 6.03 Scorpio is a difference of 83 degrees and 26 minutes. Divide that by 3, and you get about 27 deg and 48 minutes per house.

(Notice the similarity to the Placidus chart. However, a difference of a few degrees on the house cusp – e.g., 10 on the 2nd house in Porphyry vs 6 on the 2nd house in Placidus – can make a huge different when you’re tracking slow-moving transits or progressions.)

Which is best?

Personally, I’m agnostic on the subject of house systems. After keeping a spreadsheet for years that tracks transits to my house cusps in different systems, I’m still not prepared to come down on any house system as the decisive winner. Other than the angles (cusps of the 1st/7th and 4th/10th houses), which represent observable points in the daily path of the planets, house cusps are, to me, a bit like past lives: you can believe whatever you want about them and have a 50/50 chance of being right.

I think house systems are like lenses that a photographer might use on a camera. You can take a photo of the exact same subject and see it very differently, just by using a different lens. Same truth, different perspective.

So when an astrologer tells me they use their house system because “it works,” I believe them. I also believe other systems work, because I’ve seen different astrologers produce great accuracy with many house systems. And so, if a client has strong feelings on the subject and asks me to use a particular house system, I’m more than happy to use their lens.

It’s complicated

I hate to disappoint any readers who were hoping I’d settle this house system matter once and for all. It’s complicated; it has to do with the ways that we interpret a three-dimensional universe using a one-dimensional map. There’s math involved – and deep philosophical questions.

To anyone who is advanced enough in their study of astrology to ask about house systems, I always recommend that they experiment with as many as they like, and maintain a spirit of inquiry and flexibility about it. I’m not an especially flexible person by nature, but I think I’m from a generation that could afford to be a little more fluid and philosophical in our approach to things. Today, the world is harder. There’s a yearning for certainty. Returning to ancient methods and carefully defined rules and techniques perhaps reflects astrology’s evolving role as a stabilizing rudder in the world’s turbulent waves.

If you want to go with the flow and not think about this too much, just use Placidus. If you want to go with what’s currently most popular among astrologers, that would probably be Whole Signs. And if you want to use what I use because you like me, go with Koch – but by all means, have fun investigating other possibilities!

This brief video will show you how to calculate your chart using different house systems at

© 2019 by April Elliott Kent


3 comments to " House Systems: Dividing the Sky "

  • Mary Streets

    Things go better with Koch…. unless you are born on the top or the bottom of the planet. I have used equal house midheaven.. and when I cant get a handle on a chart I go for it… Placidus is like horse shoes… but close isn’t good enough. I understand Ebertin used Koch… and I think he is deadly in the prediction department. I learned astrology back before the wheel… we did the math ourselves. Software for computers was the dream, Zane Stein had just found Chiron… funny. Grant Lewi was my guru.
    So it’s Koch for me. Thanks April.

  • super article. much appreciated.

  • Heather

    Thank you for sharing Im just a beginner at so much of this but I find it more interesting the more I learn!

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