Astrological houses
Placidus
Direct answer
Placidus is a quadrant house system that divides the daily motion of the sky into house cusps and is the most common default in modern chart software.
Placidus is a widely used time-based quadrant house system.
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At a glance
- In astrology
- Placidus can create unequal house sizes and may fail or distort near extreme latitudes.
- Found in
- Houses
- Related
- Birth Chart, Zodiac, Transit
Placidus is a widely used time-based quadrant house system.
A structural orientation; exact placements depend on the chart or technique being discussed.
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What sets Placidus apart
Placidus cuts each quadrant by time: it takes the time a degree needs to travel from the meridian to the horizon and divides it into thirds. That is why its houses vary in size and why it breaks down in the far north and south. It is named for Placidus de Titis, an Italian monk and teacher of mathematics, whose Primum Mobile appeared in 1657.
- Author: Placidus de Titis, Primum Mobile, 1657
- Method: divides the time a degree takes from the meridian to the horizon into thirds
- Cusps: the 1st, 4th, 7th and 10th are the angles; the others are derived
- Failure: undefined beyond the polar circles, about 66.5 degrees of latitude
- House sizes: unequal, and more so at higher latitudes
Often mistaken for something else: Koch is another time-based quadrant system, from the 20th century, and gives different cusps. Placidus is the older of the two.
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The story behind Placidus
Placidus became especially influential in Europe and later in modern astrology through printed tables and software defaults.
The spiritual meaning of Placidus
Spiritually, Placidus asks how time, place, and incarnation shape the rooms of the chart.
Why Placidus matters
Placidus matters because many modern charts, books, and software defaults quietly assume it.
How to read Placidus
Astrologers reach for Placidus when comparing with modern psychological astrology, common online charts, or readings built around quadrant houses.
Placidus in practice: an example
In Placidus, a sign can be intercepted inside a house and a planet can change houses compared with Whole Sign.
Where readings of Placidus go wrong
It is a mistake to treat Placidus as the only correct house system just because it is common.
Sources and editorial method
This entry summarizes the tradition in the Almanac's own words; where no source is listed, it is an editorial summary rather than a primary text, and symbolic readings are named as the tradition's, not as fact.
- Source
- The Great Almanac Dictionary
- Category
- Houses
- Last updated
- 2026-09-26
Check your Placidus houses
Placidus in a book is one thing; Placidus in your own birth chart is your life. The Oracle casts your real chart and tells you what it means for your love, your work, and your year ahead, in conversation. It opens with the 7-day Seeker trial.
Speak with the OracleHow Placidus lives in your own chart across your year, in love, in work, in timing, is written in the Cosmic Codex: the whole year, once. Open the Cosmic Codex
Related terms
More in Houses
- Planet in the Ninth House
- Porphyry Houses
- Succedent Triad
- Angular Houses
- Derived Houses
- Equal Houses
- House Cusp
- Intercepted Houses
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Common questions
What is Placidus?
Placidus is a quadrant house system that divides the daily motion of the sky into house cusps and is the most common default in modern chart software.
Where does Placidus come from?
Placidus became especially influential in Europe and later in modern astrology through printed tables and software defaults.
What does Placidus mean in astrology?
Astrologers reach for Placidus when comparing with modern psychological astrology, common online charts, or readings built around quadrant houses.
What does Placidus look like in a birth chart?
In Placidus, a sign can be intercepted inside a house and a planet can change houses compared with Whole Sign.
What does Placidus mean spiritually?
Spiritually, Placidus asks how time, place, and incarnation shape the rooms of the chart.
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