Astrology: An Introduction to Decans

There are many things we do in astrology that help us hone in or the essence of the interactions of the planets in our birth chart. I like to use the analogy of a radio. You can often get to the main station’s signal, but sometimes it’s not one hundred percent clear. Maybe there is a little static. If you turn the dial of the radio right or left very slowly and tick into a slightly different frequency you can often clear things up and get much better reception. Using the information provided with decans is one of those slow turns of the knob and can really help us clarify.

This explanation is geared toward a beginner who has spent some time getting to know the basics of chart interpretation. I have offered it to beginners because I don’t think that decans are mysterious but no one told me about them until I was well into a more intermediate stage of astrological learning. Since this is a very brief overview and I will be painting in wildly broad strokes I have not included house or aspect interpretations…these you will need to add into the pot as you go along.

I use decans in a very practical manner with all charts I analyze. Initially, I will apply decan interpretation up front for the sun, moon and ascendant of every chart. This gives me a very rich personality profile without having to dig too deep. Secondly, I will apply it to planets that are very influential in a chart especially with those involved in tension based configurations such as T-squares. This is very clarifying. So I feel that this is a little tip that even beginners can use once they understand the ingredients needed to create the dish!

Is A Decan Like A Pecan?

First, let’s make sure you get that pronunciation right! Decan is pronounced “dek-an” with emphasis on the “dek.” It is shorthand for the word decanate. You’re welcome!

So, what is a decan? Here is what I assume you already know about each sign – Aries, Taurus, Gemini etc; have 30 degrees that make up the whole of the sign. The degrees start with 0 degrees of a sign and end at 29 degrees of that sign. Those thirty degrees can be divided up into three groups of 10 degrees. A 10 degree group is called a decan!

You can already see that there will be three decans per sign. Let’s take Aries as an example. This is how the decans will look:

First decan: 0 – 9 degrees of Aries.

Second decan: 10-19 degrees of Aries

Third decan: 20 – 29 degrees of Aries

So simple! The same degrees are grouped for the decans of every sign!

It’s Elementary, My Dear Friend!

Now, how does it work?

You also already know that every sign has an element: Fire, Water, Earth or Air. We will continue look at Aries for our example and Aries is a fire sign.

Every element is represented in astrology by three signs. In the chart above you can see Aries is a fire sign and so are Leo and Sagittarius.

The three signs have a maturing aspect when you work with them around the birth chart. The first sign in an element is the newest sign. It is the “newborn” of the element. The second sign in the element is a more grown up version and is more like the “young teen/young adult” of the element. The last sign in the element is the “adult” version of the element.

In our Aries example, we have Aries as the newborn fire sign, Leo is the young teen/adult fire sign, and Sagittarius is the adult fire sign.

Growth Through The Element of Fire

What do I mean by newborn, young adult and adult expressions of an element? Let’s look a bit more closely as the fire signs in a simplified manner.

Aries the Newborn – Aries is the very first sign of the entire zodiac, living in the first house of the zodiac and is the first sign of the element of fire! If we use the analogy of a human life it really IS the energy of a newborn! It sees the world as brand new, pure potential, pure inspiration and anything is possible! Babies are completely self-centered, and Aries energy can also be this way as it can be very focused on self-identity and relates everything that is happening around it to, “how does this affect me?” It is fiery and driven to explore and learn with curiosity full steam ahead.

Leo the Young Teen – As a child grows it begins to lose some of that self-only identification. It has moved through the houses of growth which involve inter-relating to a family unit, whether just with parents or combined with siblings. It rules the fifth house where we learn that there are other people in the world outside the home most notably through the act of having to go to school. Leo’s energy is full of play and creativity. It loves to party and you can’t have much of a party by yourself so it’s about learning the art of socialization with peers and making friends. Leo is also the sign that shows up when the ego is starting to feel its oats because, again, when stepping out into the land of others we are often confronted by the mirror that reflects to us perceptions about who we are in comparison to another person, or a within a group of others.

Sagittarius the Adult – Continuing on with our analogy of a child, by the time we reach the sign of Sagittarius we have done a lot of living. This roughly correlates to the ages of our mid-20’s to mid-30’s and we are now moving toward becoming established in our chosen careers through higher education, we might have a long term relationship, children, have bought a house. Sagittarius brings us into an integration with our outer lives and our sense of our inner spiritual foundation. It is far from staid as it is still a fire sign so there is a lot of action and interaction with this sign.

Now, Apply It!

Let’s summarize what we you know:

  • Each sign has 30 degrees. Those 30 degrees are divided into three groups of 10 degrees. A group of 10 degrees is called a decan. This means that each sign has three decans within it.
  • Each sign has an element (fire, water, earth, air.)
  • There are three signs for every element.

So, how does this all work? Back to Aries!

  • There are three decans in Aries,
  • Aries is a fire sign and,
  • There are three fire signs – Aries is the first, Leo is the second, Sagittarius is the third.

We now assign each one of the fire signs to each decan in the one sign we are interested in. The assignments go in order of zodiacal progression, moving counter-clockwise around the astrological chart (see image above.) So, lets look and see how that works for the sign of Aries.

  • First assignment: 0 – 9 degrees of Aries is the “Aries decan of Aries.”
  • Second assignment: 10-19 degrees of Aries is the “Leo decan of Aries.”
  • Third assignment: 20-29 degrees of Aries is the “Sagittarius decan of Aries.”

Whatever sign you are interested in, the first decan will always be it’s own sign. So, let’s now look at the second and third fire signs, Leo and Sagittarius! Here is the breakdown:


  • First assignment: 0-9 degrees of Leo is the “Leo decan of Leo.”
  • Second assignment: 10-19 degrees of Leo is the “Sagittarius decan of Leo.”
  • Third assignment: 20-29 degrees of Leo is the “Aries decan of Leo.”


  • First assignment: 0-9 degrees of Sagittarius is the “Sagittarius decan of Sagittarius.”
  • Second assignment: 10-19 degrees of Sagittarius is the “Aries decan of Sagittarius.”
  • Third assignment: 20-29 degrees of Sagittarius is the “Leo decan of Sagittarius.”

You can now work this out with all the remaining elements and their corresponding signs!

Pulling It All Together

Now lets look at this practically. Let’s look at possible interpretations for a sun at 12 degrees of Sagittarius, a moon at 12 degrees of Leo, and an Ascendant at 5 degrees of Aries. How does this help in fine tuning the interpretation of these three basic elements of a chart? (Again, I am not including anything about houses or aspects here, just a broad stroke of the way fine tuning utilizing a decan can go. The houses and aspects will also modify and fill out the picture much more .)

First, we look at the sun. At 12 degrees of Sagittarius it falls in the second decan of Sagittarius which is the “Aries decan of Sagittarius.” This means that the sun carries all the qualities of Sagittarius sun and is expressed through a more Aries-like quality. So, while Sagittarius may suggest that this is someone who is may be very interested in pursuing things like higher education, justice, and/or spiritual pursuits the way the Aries decan says that one may likely pursue these things could manifest in a very self-interested fashion. While this person might be interested, say, in the justice system, when they do get involved in that system their motivation for doing so may not come from a particularly altruistic push of helping the downtrodden seek justice. It could be a very self-serving motivation in that “being a justice seeker” is the persona they are trying to develop and maintain. Aries (the “baby” fire sign) often likes to initiate projects and programs but they can also have a hard time seeing things to completion because they lack the maturity to apply discipline so they would likely be more interested in looking like they were the one in charge than actually implementing change. Lastly, Aries is ruled by Mars so this might point to a tendency to be adversarial in approach rather than collaborative as Sagittarius is wont to do.

Next, let’s look at the moon at 12 degrees of Leo, with it falling in the Sagittarius decan of Leo. A Leo moon is nurtured and emotionally fed by all things Leonian – play, creative pursuits, socializing with friends, partying til dawn. Security will be found in having close friendships and they may thrive in being the class clown or known as the life of the party. With it falling in the Sagittarius decan you can add that Jupiter influence and this may be someone who comes off larger than life! This person might well be emotionally fed by the adoration of the theater or movies and will be very good at it, possibly a star with many accolades! The Sagittarius decan, being the “adult” decan can also lend a very mature note to this person, even while they are living large. They could appear very Leonian with a flashy presence writ large but they would have the ability to also be very intelligent and articulate and use their opportunities of interviews to discuss equality and justice for the disenfranchised.

Finally, a quick look at the Ascendant at 5 degrees Aries. No mystery here…that is an Aries rising in the Aries decan. Straight up Aries all the way! With that Aries decan it gives the Ascendant a double whammy. Their doorway to the world is framed by that fiery, inspired, initiatory Martian charge! They will just go for it and damn the torpedos!

Check Your Chart!

I hope that this has been helpful to you and that you quickly reached for your own chart to see what your sun, moon and ascendant are looking like with this added information. It might be that you suddenly understand why you have a Gemini sun but you have never really felt that you fit that bill…only to discover that your sun is in the Libra decan! So, while you might be initially OK with lots of social mental energy your sun is tampered a bit by the Libra and Venus influence and you feel that you really relate more from that heart center than your head!

Please feel free to message me if you have any questions and if this has been interesting to you do pursue further research online! There is a LOT of information about decans out there!

Be well, be happy.