Decan Rulers for All 12 Signs: Chaldean Faces and Triplicity Decans

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Each zodiac sign is split into three decans of ten degrees, and astrologers who use decans usually give each one a ruling planet. There are two common ways of doing that: the Chaldean faces and the triplicity decans. They are separate conventions and they often name different planets for the same decan.

This page is the lookup. It shows how each sequence is built, so you can check any entry yourself, then lists all 36 decans with both rulers side by side. What a decan is, and how much weight it carries in a reading, is covered on decans in astrology. Working out which decan a placement is in is covered on how to find your decan.

About this table. The table below is an educational reference that Astrologist.com publishes so the two ruler conventions can be compared; it is not something the calculator uses. The free birth chart lists sign degrees and leaves decans and their rulers unmarked. The site's dignity lookup is unchanged: it still uses only domicile, detriment, exaltation and fall, and Astrologist.com does not score faces or add dignity points for them. The chat will discuss a decan ruler if you name the placement, yet it does not look decans up from your chart.

How the Chaldean faces are built

The Chaldean faces use the seven traditional bodies in the Chaldean order, which runs from the slowest apparent motion to the fastest:

Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon.

The face sequence begins with Mars at 0° Aries and then moves one step along that order for each new decan, wrapping from the Moon back to Saturn. In practice the run reads Mars, Sun, Venus, Mercury, Moon, Saturn, Jupiter, then Mars again, and so on. Aries takes Mars, the Sun and Venus; Taurus takes Mercury, the Moon and Saturn; Gemini takes Jupiter, Mars and the Sun; and the pattern carries on to the end of Pisces.

Two things follow from that construction. First, there are no outer planets anywhere in the faces. Uranus, Neptune and Pluto were unknown when the scheme was fixed, and adding them would turn it into a different system. Second, 36 decans divided among seven planets leaves one over, because 36 is five rounds of seven plus one. The last face of Pisces therefore goes to Mars, and so does the first face of Aries, the only place where one planet rules two faces in a row.

How the triplicity decans are built

The triplicity decans follow the elements. Each sign's three decans are associated with the three signs of its own element, starting with the sign itself and continuing in zodiac order. A fire sign's decans go to fire signs, an earth sign's to earth signs, and so on:

• Fire: Aries gives Aries, Leo, Sagittarius; Leo gives Leo, Sagittarius, Aries; Sagittarius gives Sagittarius, Aries, Leo.
• Earth: Taurus gives Taurus, Virgo, Capricorn; Virgo gives Virgo, Capricorn, Taurus; Capricorn gives Capricorn, Taurus, Virgo.
• Air: Gemini gives Gemini, Libra, Aquarius; Libra gives Libra, Aquarius, Gemini; Aquarius gives Aquarius, Gemini, Libra.
• Water: Cancer gives Cancer, Scorpio, Pisces; Scorpio gives Scorpio, Pisces, Cancer; Pisces gives Pisces, Cancer, Scorpio.

The ruler of each decan is the ruler of the sign it is associated with. Astrologist.com follows modern-first rulership with the traditional rulers retained, so wherever a decan is associated with Scorpio, Aquarius or Pisces, the table names the modern ruler first and the traditional ruler beside it: Pluto with Mars, Uranus with Saturn, Neptune with Jupiter. Modern and traditional rulers explains why the site keeps both.

This convention is not the same thing as the traditional dignity called triplicity. Both use the same grouping of signs by element, but they use it differently: triplicity decans link the three thirds of a sign to the three signs of its element, while the triplicity dignity assigns planetary rulers to each element, traditionally with separate day and night rulers. The elements are explained on zodiac elements explained.

All 36 decans and their rulers

Degree spans are written in whole-minute shorthand. The exact rule is that each decan starts at its first degree and ends just before the next boundary, as set out on how to find your decan.

Read across a row, not down a column. The face ruler and the triplicity ruler are answers from two different conventions; they are not meant to be combined into one ruler for the decan.

Where the two conventions agree and differ

For most decans the two conventions name different planets. They name the same planet in six decans using the modern-first rulers: the first and second decans of Aries (Mars, then the Sun), the third decan of Taurus (Saturn), the second and third decans of Leo (Jupiter, then Mars) and the second decan of Aquarius (Mercury). If you read the triplicity decans with the traditional rulers instead, three more coincide: the second decan of Libra (Saturn), the first decan of Scorpio (Mars) and the third decan of Pisces (Mars).

The first decan of every sign is a useful check on how differently the two work. In the triplicity decans, the first decan always belongs to the sign's own ruler. In the Chaldean faces it often does not: the first face of Taurus is Mercury rather than Venus, and the first face of Cancer is Venus rather than the Moon.

Because the systems disagree so often, a decan ruler means little unless the convention is named. If you use decan rulers at all, choose one convention, say which one you are using, and keep to it for the whole chart.

Faces as a minor dignity

In traditional astrology, a planet in its own face is said to have a small essential dignity, the weakest of the traditional set. Astrologist.com names the concept so the term is recognisable, and this table lets you see which planet holds each face. The site does not go further than that. The dignity lookup on planetary dignities explained still covers only the four main conditions, set out in more depth on domicile and detriment and exaltation and fall. No face is counted as a point, and no planet is ranked as stronger or weaker because of the face it occupies.

Reading a decan ruler without overreading it

A decan ruler is a secondary note on a placement that is already defined by its planet, sign, house and aspects. The sign's own ruler still disposes the planet, and the decan does not change the sign. For example, on Ruben's date at 12:00 his Sun is 15°10' Capricorn, the second decan, which this table gives to Mars as a face and to Taurus, ruled by Venus, as a triplicity decan. His Sun is still a Capricorn Sun with Saturn as its sign ruler; the decan ruler is a small extra colour, read in one convention or the other. The full worked example, including the time-sensitive placements, is on how to find your decan.

There are no decan personality profiles on this site, and no decan is presented as better than another. Decan rulers describe tendencies within a sign, not outcomes.

Next steps

Find your degrees on the free birth chart, look each one up in the table above, and keep the two columns apart. The methodology page lists the site's zodiac and rulership choices. To discuss a ruler you have found, ask the Astrologist with the placement and the convention you are using.

Related articles

• Decans in Astrology
• What Decan Am I? How to Find Your Decans
• Planetary Dignities Explained
• Domicile and Detriment in Astrology
• Exaltation and Fall in Astrology
• Modern and Traditional Rulers
• Zodiac Elements Explained
• Zodiac Signs