The Ultimate Astrology Decan Chart: A Cheat Sheet for Deep Divers

So you've figured out that your Sun sign is just the beginning of your astrological story. You know there's more depth to explore, more nuance to uncover. That's where decans come in, and if you're ready to get serious about understanding your chart, you're going to need a reference guide.

This is that guide. Consider it your decan cheat sheet, the thing you bookmark and come back to whenever you're deep-diving into placements. We're breaking down what a decan chart actually is, how to read it, who rules what, and how to apply this knowledge to your own chart. Let's get into it!

What Exactly Is a Decan Chart?

A decan chart is basically your roadmap to the more granular layers of astrology. Instead of just knowing you're a Virgo or that your Venus is in Scorpio, decans help you understand which flavor of that sign you're expressing.

Here's the deal: every zodiac sign spans 30 degrees around the zodiac wheel. A decan divides each sign into three equal 10-degree segments. Each of those segments has its own planetary ruler that adds extra texture and meaning to the sign's baseline energy.

Think of it like this, if your Sun sign is the genre of music you vibe with, your decan is the specific subgenre. You're not just "into rock," you're specifically into indie folk rock from the Pacific Northwest. That's the kind of precision decans give you.

The Three-Decan Breakdown

Every zodiac sign gets split into three decans:

• First Decan (0–10°): Ruled by the sign's primary planetary ruler. This is the "purest" expression of the sign.
• Second Decan (10–20°): Ruled by a secondary planet that modifies and adds complexity to the sign's energy.
• Third Decan (20–30°): Ruled by yet another planet, adding even more layers of nuance.

The planetary rulers follow something called the Chaldaean order, which is an ancient astrological system that sequences the planets by their apparent speed through the sky. The order goes: Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon. This sequence repeats across all twelve signs in a specific pattern.

Why does this matter? Because those secondary rulers change how you express your sign. A first-decan Leo (ruled purely by the Sun) is going to feel different from a third-decan Leo (with Mars co-piloting). Same sign, different vibe.

The Master Decan Chart (Bookmark This!)

Alright, here's the part you're really here for, the full breakdown of every sign's decan rulers. Save this table. Print it out. Tattoo it on your forearm if you're that committed to the craft.