Decans (Zodiac Sub-Traits)
See finer innate traits from your decan (10°), each sign split into three.
A decan is a 10° subdivision of each zodiac sign (30°) in Western astrology, dividing every sign into three. Even within the same sign, your decan carries a different sub-ruler (traditional triplicity), giving subtly different traits. Find your decan and its sub-ruler by your birth date and explore your personality, love, and work tendencies in finer detail. Dividing the sky into thirty-six comes from the Egyptian decans, thirty-six groups of stars used to tell the hours of the night, and Hellenistic astrology laid them over the twelve signs to give the present arrangement. There is more than one way to assign the sub-ruler; here we use the traditional triplicity, cycling through the rulers of the three signs that share an element. Results may therefore differ from tables that assign sub-rulers in Chaldean order.
How it works
Enter your birth date and we find your sun sign, then which of its three decans you fall in — the thirty degrees of a sign split into ten-degree thirds. Only the date is needed; the birth hour is not used.
What you'll get
You see the character of your decan and the sub-ruler that governs it alongside your sign, the texture of love and work, and this year's flow as the sub-ruler shapes it. Money and health also turn on which planet co-rules the decan, so those two come out decan by decan.
A sky in thirty-six parts began as a calendar
In ancient Egypt the stars of the night sky were sorted into thirty-six groups, and the season was reckoned by watching one of those groups rise for the first time before dawn every ten days. Thirty-six multiplied by ten gives three hundred and sixty, so the decans were at once a scale for telling the hour at night and a calendar for cutting up the year. Those thirty-six divisions were later laid over the twelve signs of the zodiac, and that is where the decans of today come from.
Birthdays on the edge of a decan
A decan is ten degrees, which works out at roughly ten days. So when a birthday falls where one decan gives way to the next, whether it belongs to the earlier or the later one depends on the hour the sun crossed that boundary. If you were born around a changeover, read both descriptions and take as your own the one that draws more nods from you. Nothing is lost by keeping a foot in both, since neighbouring decans share the same sign anyway.
A shared sub-ruler links you to another sign
The method used here settles the sub-ruler of each decan by cycling the rulers of the three signs that share an element. As a result, your sub-ruler is often a planet that rules not your own sign but another of the same element. When that happens, traits belonging to that other sign show up alongside your own. Something about yourself that the description of your sign never accounted for sometimes comes clear here.
Why books disagree about the sub-ruler
There is more than one way of assigning planets to decans. Besides the traditional triplicity method used on this page, the Chaldean method, which cycles the seven planets from Saturn down to the Moon, is widely used. The two tables disagree often, so if a sub-ruler you saw in another book or on another site differs from the one here, neither is wrong: they follow different tables. Checking which method is in use first saves a good deal of confusion.
Do not judge people by their decan
Even divided into decans there are only thirty-six segments, so hundreds of millions of people fall into any one of them. Looking at finer detail does not mean pinning down an individual. Please refrain from asking someone their birthday, working out their decan and sizing them up by it. A place to narrow down the gap when the description of your sign never quite fitted is about what a decan is for.
Frequently Asked Questions
How is a decan different from a sign?
It is a subdivision: the thirty degrees a sign covers, split into three ten-degree parts. Even within one sign, the beginning, middle, and end read differently.
How is my decan decided?
It follows from which ten-day stretch of the sign your birthday falls in. There is nothing to choose by hand.
Should I read this alongside the horoscope?
They work well together. The horoscope covers what shifts with time — today, this week — while your decan is fixed at birth and never changes. When the two say different things, that is the day’s flow pulling against your inborn grain, and that gap is worth reading.
What is the sub-ruler?
The planet considered to co-rule that ten-degree stretch. It is assigned separately from the sign's overall ruler, so two people of the same sign in different decans have different sub-rulers and read differently.
Can I find my decan from a lunar birthday?
You can, but a decan is fixed by where the sun sat on the ecliptic, so the solar date is the reference. Choose lunar and it is converted first, then the decan for that date is looked up. The two calendars can sit nearly a month apart, so the wrong choice changes even the sign.