Decans in astrology: the 36 decans, dates, and rulers
Each sign is divided into three parts of about ten days, which add nuance to its character.
- 36 decans
- Chaldean faces
- triplicities
By Thomas Guilhot · updated
The decans at a glance
The decan refines the Sun sign: it places the Sun in the first, second, or last third of the sign.
- How many
- 36: three per sign
- The Sun today
- 3rd decan of Libra
- Duration
- About ten days each
Two ways to name the rulers
Both systems share the same 36 slices of 10°; they differ in the planet they assign to each. Both are given here, without choosing.
- The facesChaldean order
- Rule
- Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon, in a loop
- Start
- Mars, 1st decan of Aries
- Sources
- Hellenistic tradition; William Lilly, Christian Astrology (1647)
Each planet rules five or six decans; the sequence continues from one sign to the next and closes at the 3rd decan of Pisces (Mars).
- The triplicitiesSystem of signs
- Rule
- The three signs of the element, in zodiac order
- Example
- Aries: Aries, Leo, Sagittarius
- Sources
- Drekkana of Indian astrology; modern astrology (Alan Leo)
A decan’s ruler is the ruler of the sign that corresponds to it: Mars, the Sun, then Jupiter for Aries.
The faces follow a fixed order, that of the planets ranked from slowest to fastest: Saturn, Jupiter, Mars, the Sun, Venus, Mercury, the Moon. The series begins with Mars at the start of Aries and continues without interruption through to Pisces. It produces associations that are sometimes unexpected, such as Saturn in the first decan of Leo.
The triplicities work by element. The first decan belongs to the sign itself, the second to the next sign of the same element, the third to the last: for Scorpio, a water sign, that gives Scorpio, Pisces, Cancer. The ruler is the lord of that sign. The two systems agree on a few decans and diverge on most.
Each sign, three decans
Dates calculated for 2026 (Sun’s entry, Paris time); rulers: faces, then triplicity.
Aries
Taurus
Gemini
Cancer
Leo
Virgo
Libra
Scorpio
Sagittarius
Capricorn
Aquarius
Pisces
What tradition says about the decans
The decans are said to come from Egypt. The Egyptians identified 36 stars or star groups whose successive risings marked the hours of the night, and the lids of some sarcophagi carry lists of them in the form of tables. Greek astrologers in Alexandria would later have fitted these 36 divisions into the twelve signs, three per sign.
The Middle Ages and the Renaissance gave them images: the Picatrix, a treatise on magic translated from Arabic, describes a figure for each decan, and the frescoes of the Palazzo Schifanoia in Ferrara paint them month by month. In India, the drekkana of Varahamihira follow the principle of the triplicities, taken up by Alan Leo in the early 20th century.
Frequently asked questions about the decans
What is a decan in astrology?
A decan is a 10-degree slice of the zodiac, one third of a sign. There are 36 of them. The Sun takes about ten days to cross one, which is why people commonly speak of the first, second, or third decan of a sign depending on the birth date. Tradition assigns a planet to each decan, which would add nuance to the reading of the sign without replacing it.
How do I find my decan?
The decan depends on the Sun’s degree within its sign: from 0 to 10 degrees, first decan; from 10 to 20, second; from 20 to 30, third. Because the dates when the Sun enters a sign shift slightly from year to year, the boundaries of the decans move too. The “what is my sign” tool calculates the degree for your date; the page for each decan gives the dates through the year.
Faces or triplicities: which system should I choose?
Neither is truer than the other; they come from different traditions. The faces, in Chaldean order, belong to Hellenistic and medieval astrology, that of Lilly. The triplicities, close to the Indian drekkana, dominate modern astrology and the press. The site gives both rulers side by side: comparing the two readings is more instructive than dismissing one outright.