One of the most disconcerting surprises when we begin to explore astrology is realizing that the houses in our natal chart can change . Perhaps we downloaded our chart from a free website, analyzed it carefully, and became attached to the idea of ​​having Venus in the 5th house, for example. But then we go for a reading with an astrologer and they tell us it's in the 6th house. How is that possible?

The answer has to do with something that's often not widely known: there are different systems for calculating houses . And no, there isn't one that's "right" and the others that are "wrong."

A Technical Detail That Changes a Lot

When we look up our birth chart online, the default system is most likely the Placidus house system, simply because it's the most popular. But that doesn't mean it's the only one, nor necessarily the most appropriate for every case.

There are actually more than a dozen house systems —some ancient, some more modern—and each uses a different way of dividing the sky into twelve sectors. This means that the position of the planets in each house can vary from one system to another, even if the time and place of birth are the same.

It's Not a Mistake, It's a Difference in Approach

When someone new to astrology encounters this detail, it's common to feel confused or even frustrated. Which of these versions is true? How can my birth chart change?

But these aren't errors or contradictions. Each house system represents a different way of looking at the same thing . Some prioritize the more external experience, others show a more symbolic or psychological organization of space, and still others focus on the rhythms of the Earth and the sky. Therefore, it's entirely possible for a planet to be located in the 10th house according to one system and the 11th according to another—and for both interpretations to say something true about the person.

Where Are Some House Systems Used More Than Others?

When delving into the world of house systems, it's helpful to know that the popularity of each system varies by region or astrological tradition . This can help us understand why different astrologers or platforms use some systems over others.

1. West (United States and Europe)

• The Placidus system is the most widely used in modern Western astrology. Not so much because it's the most successful or the best, but because it's the default system on many websites and free programs, and that's why it has become the "default" house system.

• In the United States, the Koch system (this is the one we use in 8th House Astrology) and Equal are also commonly used. In particular, it is estimated that over 80% of American astrologers use Placidus, followed by Koch and then Equal.

• In German-speaking countries, the Koch system is quite prevalent, and alternatives such as the Krusinski (or Krusiński) have also been developed.

• Lately, the Whole Sign Houses —an ancient and simplified system—has been gaining ground in the West, becoming the second most widely used system after Placidus among some groups of astrologers and enthusiasts.

2. Hellenistic Tradition and Classical Studies

• The Whole Sign system, which assigns each house to a complete sign, was the original method used in Hellenistic astrology (as in Ptolemy)  .

• It was rediscovered and popularized again in the West in the 1980s and 1990s, and has been adopted by many astrologers working with traditional astrology.  .

3. Indian Tradition (Jyotisha/Vedic)

• In India, Vedic astrology traditionally employs systems of bhāvas , which are equivalent to our houses, divided equally into 30° each , starting from the Ascendant.

• Although not exactly the same as the Western Whole Sign system (each sign = one house), the equitable and symmetrical approach is very common in that tradition.

Which One to Keep?

There's no need to choose a house system just as we're starting out. The important thing, at the beginning, is to know that this difference exists . And that if we change programs or astrologers and see that the houses have shifted, it doesn't mean our chart is "wrong."

Over time, if we continue to dig deeper, we can explore the different house systems, seeing which one resonates most with our way of looking at the world—or even use them in combination, depending on the type of reading we want to do.

In a future post, we will explain what each of the most commonly used systems consists of.