As those of us absorbed by astrology are well aware, your sun sign can only tell you so much about yourself. Beginners might look to their moon or rising sign for more information, for example, while those who are more advanced in their zodiac journey might want to dig into more intricate concepts—like astrology decans (also called “decantes”). “If you’ve ever wondered why people born in the same sign seem different, decans can help answer this puzzle,” says astrologer and intuitive healer Rachel Lang.

“If you’ve ever wondered why people born in the same sign seem different, decans can help answer this puzzle.”—Rachel Lang, astrologer

To understand decans, you must first understand that each astrological sign occupies 30 degrees of the Zodiac, Lang explains, for a total of 360 degrees (12 signs are each comprised of 30 degrees). Decans are subdivisions of 10-degree increments per sign, which is 30 degrees. Your decan, then, is wherever your birthday falls within that 30-degree spread.

Approximately the first ten days of your sign is the first decan, approximately the second ten days of your sign is the second decan, and approximately the third ten days is the third decan. If it doesn’t make sense yet, don’t worry, we’ve got you covered. Read on to learn more about astrology decan, how it impacts your personality, and what yours says about you.

What are decans in astrology?

Each decan has a unique footprint, so to speak. “Within these decans, we assign planetary sub-rulers to the sign, and those sub-rulers give us additional layers of symbolism to apply to your birth date within your sign,” Lang explains. BTW, sub-rulers refer to the ruler of each decans, much like the chart rulers that reign over our natal chart. Per Erin River Sunday, an astrologer and co-host of the Kiss My Astral podcast, you can think of sub-rulers as the “flavor” of each decan, as they determine the cosmic energies of the degree of that sign.

“We assign planetary sub-rulers to the sign, and those sub-rulers give us additional layers of symbolism to apply to your birth date within your sign.”—Rachel Lang, astrologer

That said, “If you are born within the first decan, or the first ten degrees (approximately ten days) of a sign, you embody your sign to the fullest. Your planetary sub-ruler is going to be your sign’s ruler,” says Lang. If you’re not the first decan, your sub-ruler gets a bit trickier to discern. Basically, Lang says that you need to look at the triplicity of your sign—whether it’s an air, water, fire, or earth sign—in order to figure it out.

While the first decan is assigned the same ruler of their sun sign, the second decan is assigned the secondary ruler of the next sign within that same element, and the third decan is assigned the secondary ruler of the next sign after that (within the same element).

Sunday says that each planetary sub-ruler of the decans can be likened to the evolution of energy within each sign. “If we think about the decans as a karmic journey, with the degrees indicating where we are along the path within that sign, we can begin to understand compatibility on a soul level,” says Sunday. The first decan is the fullest embodiment of a sign, representing the beginning of a soul journey, while the third decan is a bit more rounded as it’s the last decan.

Below, Lang guides us through how to interpret decans in your birth chart.

How do you interpret the decan in astrology?

In astrology, decans are just another way to categorize the individual zodiac signs. By separating a zodiac sign in three parts, we can see why people born under one zodiac sign may have different qualities.

As the first zodiac sign, let’s take Aries for example. Lang says that if you’re an Aries born between March 21 and 30 (with the caveat that this could vary depending on the day the sun enters that sign), you were born in the first decan, so your sub-ruler is the same as the ruler for your entire sign: Mars. “Mars is courageous, independent, and driven,” she says. “It’s the warrior planet. You are a pioneer and ready to take a risk.”

An Aries born between approximately March 31 and April 9, meanwhile, is the second decan. Since the next fire sign in the Zodiac is Leo, and Leo is ruled by the Sun, Aries’ second decan’s sub-ruler is the Sun. “Your main ruling planet is still Mars, but we add the Sun as a planetary sub-ruler,” Lang explains. “The Sun’s influence gives you a strong desire to lead and make a difference. You can be strong-willed and appear confident to others, but at times, others might perceive you as selfish.”

Finally, an Aries born between April 10 and 20 is in the third decan. And since the next fire sign in the Zodiac is Sagittarius, and Sagittarius is ruled by Jupiter, the third decan’s sub-ruler is Jupiter. “Jupiter adds optimism and enthusiasm to the Mars influence,” says Lang. “Freedom is a keyword for you.”

While Lang doesn’t break down each decan in this level of detail below, she does offer guidance as to which decan you may be as well as what that decan’s sub-ruler is. “If you want to find out more about your decan, look at the symbolism for the sign,” she says. In other words, do a little DIY investigation into the influence of your particular sub-ruler—whether it be the Sun, Mercury, or Saturn—to add some layers to your astrological self-awareness (or stalking—I mean, understanding—of someone else).

How do decans affect zodiac sign characteristics?

Your birth chart is composed of information such as your “big three,” along with astrological houses and even the placements of the planets in your chart. As Sunday explains, “Decans attempt to illustrate the evolution of energy within a single sign in astrology. It’s obvious that as a sign changes from one to the next, the energy shifts, but the same thing happens, more subtly, within any individual sign as well.”

Decans give you deeper insight into the qualities of those in your element; air signs will have decans in the air element, Earth signs in the Earth element, and so on. So, if you’ve ever struggled to relate to other people who share your zodiac sign, it might be due to a number of the aforementioned elements, but it could also be that you fall under a certain decan.

A personal example: I’m an Aquarius, but I have always felt alone in being a romantic, despite the water bearer being known for their unemotional and less-than-romantic ways. When I learned that my birthday fell under the third decan, aka Libra, it made sense that my secondary ruler, Venus, is the planet of love and relationships. In other words, it’s possible that your decan can discern certain qualities of your element that aren’t exclusive to your sun sign.

Do decans impact zodiac compatibility?

While decans can discern key traits of your personality, it’s not typically the first thing astrologers like Sunday look at when determining compatibility. It’s more so an analysis of your personal karmic journey, explains Sunday. However, understanding your partner’s decan can give you more insight into how they operate, so it’s a good thing to consider—but not hinge your astrological compatibility on.

How to find your decan, and planetary sub-ruler

Aries: March 21 to April 19

Aries is ruled by Mars—the planet of action, energy, passion, and aggression—so it really supercharges the already fiery Aries. As a result, those born under the Aries sign tend to be confident, competitive, ambitious, independent, and a bit combative.

March 21 to March 30 (approximately) is an Aries decan, ruled by Mars. So, people born on these days will possess the aforementioned Aries traits.

March 30 to April 9 (approximately) is a Leo decan, so the Sun is its secondary ruler. Individuals born in this decan will take on characteristics typical of someone sun-ruled in addition to their primary Aries/Mars traits. They might, for example, love being the center of attention and be more creative than other Aries.

April 10 to April 19 (approximately) is a Sagittarius decan, so Jupiter is its secondary ruler. Someone born in this decan might therefore be even more adventurous than other Aries as well as more philosophical, open, and optimistic.

Taurus: April 20 to May 20

Taurus is ruled by Venus, the planet of love, sensual pleasure, and decadence. As a result, typical Tauruses are interested in aesthetics and like to engage their senses—smell, touch, taste, see, hear—as much as possible. They may also be obsessed with life’s luxuries.

April 20 to April 29 (approximately) is a Taurus decan, ruled by Venus. People born in this decan will therefore have hallmark traits of a Taurus.

April 30 to May 9 (approximately) is a Virgo decan, so Mercury is its secondary ruler. Individuals who fall under this second decan, then, are likely to be even more communicative than your typical Pisces. They may also be more intellectual.

May 10 to May 19 (approximately) is a Capricorn decan, so Saturn is its secondary ruler. These third-decan Pisces may as a result be more responsible and hardworking than a typical Pisces.

Gemini: May 21 to June 20

Gemini is ruled by Mercury, the planet of communication and intellect. As a result, Geminis tend to be social, curious, quick-witted, and knowledgeable.

May 21 to May 30 (approximately) is a Gemini decan, ruled by Mercury. Those born in this decan will possess classic Gemini traits.

May 31 to June 9 (approximately) is a Libra decan, so Venus is its secondary ruler. Geminis born in the second decan will be more sensual and tactile than other Geminis.

June 10 to June 20 (approximately) is an Aquarius decan, so Uranus is its secondary ruler. Individuals born within this decan will be more independent, rebellious, and innovative than other Geminis.

Cancer: June 21 to July 22

Cancer is ruled by the Moon, which controls human emotion as well as emotional comfort. For this reason, Cancers tend to be sensitive, intuitive, nurturing, deep, and sometimes mercurial.

July 21 to June 30 (approximately) is a Cancer decan, ruled by the Moon. People born under the first decan will present as typical Cancers.

July 1 to July 10 (approximately) is a Scorpio decan, so Pluto is its secondary ruler. Those born within this decan, then, will be more intense and inwardly focused than other Cancers.

July 11 to July 22 (approximately) is a Pisces decan, so Neptune is its secondary ruler. Individuals born under this decan will be more creative and spiritually-minded than other Cancers.

Leo: July 23 to August 22

Leo is ruled by the Sun, which brings warmth, radiance, and attention to the sign. As a result, Leos tend to light up every room they enter and enjoy widespread popularity—along with the confidence that brings. They also tend to be extremely energetic and can create a whirlwind atmosphere around themselves.

July 23 to August 1 (approximately) is a Leo decan, ruled by the Sun. People born in this decan will possess key Leo traits as mentioned above.

August 2 to August 11 (approximately) is a Sagittarius decan, so Jupiter is its secondary ruler. People born in this decan will be even brighter (read: more fun) than typical Leos and tend to love taking their party on the road for an adventure.

August 12 to August 22 (approximately) is an Aries decan, so Mars is its secondary ruler. Those born in this decan will be more explosive and aggressive than a typical Leo—their sun can turn to fire in an instant.

Virgo: August 23 to September 22

Virgo is ruled by Mercury, the planet of communication and intellect. The latter is more so the trait emphasized in Virgos, who tend to be deep thinkers. Mercury also influences Virgos to be organized, detail-oriented, and always on time.

August 23 to September 1 (approximately) is a Virgo decan, ruled by Mercury. Individuals born under this decan will present as classic Virgos.

September 2 to September 11 (approximately) is a Capricorn decan, so Saturn is its secondary ruler. This means that those born under the second decan may be more determined and hardworking than other Virgos.

September 12 to September 22 (approximately) is a Taurus decan, so Venus is its secondary ruler. This means that those born within the third decan may be more attuned to aesthetics than others of their sign.

Libra: September 23 to October 22

Libra is ruled by Venus, the planet of love and sensual pleasure. The former is emphasized in Libras, who tend to be super romantic, but they also have an interest in and gift for aesthetics.

September 23 to October 2 (approximately) is a Libra decan, ruled by Venus. People born in this decan will have typical Libra attributes.

October 3 to October 12 (approximately) is an Aquarius decan, so Uranus is its secondary ruler. This means that those born in the second decan of Libra may be more into expanding their consciousness—through things like astrology—than other Libras. They may also be more inventive.

October 13 to October 22 (approximately) is a Gemini decan, so Mercury is its secondary ruler. These Libras will then be good—and active—communicators.

Scorpio: October 23 to November 21

Scorpio is ruled by Pluto, the planet of darkness and mystery. Those born to this sign tend to be intense, enigmatic, calculating, passionate, and seductive as a result.

October 23 to November 1 (approximately) is a Scorpio decan, ruled by Pluto. Those born in the first decan will have the main characteristics of a Scorpio.

November 2 to November 11 (approximately) is a Pisces decan, so Neptune is its secondary ruler. Individuals born within this second decon, then, will be more imaginative and creative—and less grounded—than other Scorpios.

November 12 to November 21 (approximately) is a Cancer decan, so the Moon is its secondary ruler. These Cancers are more sensitive than others, and they also tend to be great caretakers.

Sagittarius: November 22 to December 21

Sagittarius is ruled by Jupiter, the planet of fortune and adventure. As a result, those born under this sign tend to be optimistic, free-spirited, and always up for a novel experience.

November 22 to December 1 (approximately) is a Sagittarius decan, ruled by Jupiter. People born within this decan will possess typical aforementioned Sagittarius traits.

December 2 to December 11 (approximately) is an Aries decan, so Mars is its secondary ruler. Those who fall within this decan will therefore be more fiery and confident than others of their sign.

December 12 to December 21 (approximately) is a Leo decan, so the Sun is its secondary ruler. Individuals born in the third decan may be more energetic, charismatic, and self-involved than others of their sign.

Capricorn: December 22 to January 19

Capricorn is ruled by Saturn, the planet of discipline, hard work, and ambition. As a result, Capricorns are all of those things—hardworking, disciplined, and ambitious. They live to crush even the most challenging of goals.

December 22 to December 31 (approximately) is a Capricorn decan, ruled by Saturn. Those born in the first decan will present as typical Capricorns.

January 1 to January 10 (approximately) is a Taurus decan, so Venus is its secondary ruler. Individuals within this decan are more sensual and romantic than typical Capricorns. They may tend to indulge in fantasy and favor decadence wherever they can find it.

January 11 to January 19 (approximately) is a Virgo decan, so Mercury is its secondary ruler. The Capricorns tend to put their ambitions and efforts toward intellectual pursuits.

Aquarius: January 20 to February 18

Aquarius is ruled by Uranus, the planet of individuality and radicalism. Those born to this sign tend to be ahead of their time, extremely innovative, and a bit eccentric.

January 20 to January 29 (approximately) is an Aquarius decan, ruled by Uranus. Those born in this first decan will have typical Aquarius traits.

January 30 to February 8 (approximately) is a Gemini decan, so Mercury is its secondary ruler. Second-decan Geminis tend to be more intellectual (and chatty!) than other Aquariuses as a result.

February 9 to February 18 (approximately) is a Libra decan, so Venus is its secondary ruler. As such, people born within this decan may be more interested in life’s pleasures, including love, than other Aquarius folks.

Pisces: February 19 to March 20

Pisces is ruled by Neptune, the planet of imagination and spirituality. Typical Pisces individuals are therefore creative, intuitive, and intense emotionally. They tend to be on, or seeking a spiritual path.

February 19 to February 28 (approximately) is a Pisces decan, ruled by Neptune. Those born within this decan will have the trappings of a Pisces.

March 1 to March 10 is a Cancer decan (approximately), so the Moon is its secondary ruler. These Pisces will be even more sensitive than their already-sensitive Pisces peers.

March 11 to March 20 (approximately) is a Scorpio decan, so Pluto is its secondary ruler. Those born within this decan will be more secretive, mysterious, and calculating than your average Pisces.