// ASTROLOGY BASICS
Your Western (tropical) zodiac sign is determined entirely by your birth date — nothing else. It's assigned by which of twelve roughly month-long date ranges your birthday falls into, a system that's been stable for centuries. The date-range part is simple, verifiable calendar fact. What each sign supposedly says about your personality is tradition and folklore, not something any study has demonstrated — worth knowing going in, and worth enjoying anyway.
Aries
Mar 21 – Apr 19
Bold, direct, first to start and first to get bored waiting for everyone else.
Taurus
Apr 20 – May 20
Steady, sensory, allergic to being rushed into anything.
Gemini
May 21 – Jun 20
Curious, quick, already three conversations ahead of this one.
Cancer
Jun 21 – Jul 22
Protective, intuitive, remembers everyone's context better than they do.
Leo
Jul 23 – Aug 22
Warm, expressive, genuinely happier when the room is having a good time.
Virgo
Aug 23 – Sep 22
Precise, useful, already noticed the thing you were about to point out.
Libra
Sep 23 – Oct 22
Diplomatic, aesthetic, weighing both sides longer than anyone asked for.
Scorpio
Oct 23 – Nov 21
Intense, private, notices what people are actually saying underneath it.
Sagittarius
Nov 22 – Dec 21
Direct, adventurous, allergic to small talk and small plans alike.
Capricorn
Dec 22 – Jan 19
Disciplined, patient, playing a longer game than most people realize.
Aquarius
Jan 20 – Feb 18
Independent, idea-driven, three steps ahead and mildly bored explaining why.
Pisces
Feb 19 – Mar 20
Empathetic, imaginative, absorbs a room's mood faster than it can absorb theirs.
You may have seen slightly different boundary dates on different sites — that's real, and it's because the exact moment the sun crosses into the next constellation shifts by up to a day depending on the year, due to how the calendar and the solar year don't divide evenly. Most sources round to the same commonly-used dates, which is what we've used above.
Your zodiac sign is just the start. DECODE.SYS pairs it with your lucky numbers, lucky stone, lucky hour, and moon-cycle day — all computed from your actual birthdate.
RUN YOUR FREE SCAN →What's the difference between a "sun sign" and my full birth chart?
Your sun sign (what most people mean by "my zodiac sign") is based only on your birth date. A full birth chart also factors in the exact time and location of your birth, and includes many more placements — moon sign, rising sign, and so on — which is a much more involved calculation.
Can my zodiac sign change?
No — like your life path number, it's fixed to your birthdate and stays the same for life.