Astrological Signs
Find Western zodiac sign from birthdate.
About the Astrological Signs
Your sun sign is decided by where the sun sat against the constellations on the date you were born. Find yours, plus the dates for all twelve.
How to use it
- Enter your birth date.
- Read your sun sign and its date range.
The formula
A sun sign is determined by where the sun appeared along the ecliptic on the date of birth, divided into twelve equal 30° segments.
360° of ecliptic ÷ 12 signs = 30° each ≈ one calendar month
Western astrology uses the tropical zodiac, which fixes 0° Aries at the March equinox. Vedic astrology uses the sidereal zodiac, anchored to the actual constellations. They agreed roughly two thousand years ago and have drifted about 24° apart since — nearly a full sign.
The cause is precession: Earth's axis wobbles over a 26,000-year cycle, moving the equinox slowly against the stars. This is why someone born a Taurus by Western dates is often an Aries by the constellations, and why the constellation boundaries the International Astronomical Union defined in 1930 include a thirteenth, Ophiuchus, that no zodiac uses.
Worked examples
| Sign | Tropical dates | Element | Quality |
|---|---|---|---|
| Aries | 21 Mar – 19 Apr | Fire | Cardinal |
| Cancer | 21 Jun – 22 Jul | Water | Cardinal |
| Libra | 23 Sep – 22 Oct | Air | Cardinal |
| Capricorn | 22 Dec – 19 Jan | Earth | Cardinal |
These four are the cardinal signs, and they are not scattered at random — each begins at a solstice or an equinox. Aries opens at the March equinox, Cancer at the June solstice, Libra at the September equinox and Capricorn at the December solstice. The zodiac's structure is anchored to the solar year, which is why the dates shift by a day between years but never drift far.
Common mistakes
- Assuming the dates are fixed. Sign boundaries move by up to a day between years, because the equinox does not fall at the same clock time annually. Birthdays on a boundary need the exact time and place to resolve.
- Confusing sun signs with constellations. The tropical zodiac is tied to the equinox, not to the stars. Precession has moved the two roughly a full sign apart over two millennia.
- Treating a sun sign as a whole chart. In astrological practice it is one placement among many — the moon, the rising sign and planetary positions are all part of a natal chart, which requires a birth time.
- Expecting predictive validity. Controlled studies have consistently failed to find that astrological placements predict personality or events. Readings feel accurate largely through the Barnum effect.
Terms explained
- Ecliptic
- The apparent path of the sun across the sky over a year. The band the zodiac divides.
- Tropical zodiac
- The Western system, anchored to the March equinox at 0° Aries.
- Sidereal zodiac
- The system used in Vedic astrology, anchored to the constellations. About 24° from the tropical zodiac today.
- Precession
- The slow wobble of Earth's axis over roughly 26,000 years, which moves the equinox against the background stars.
- Cusp
- The boundary between two signs. Astrologically a birth falls on one side or the other — the exact time settles it.
- Ophiuchus
- A thirteenth constellation the sun passes through, included in the IAU's 1930 boundaries and used by neither zodiac.
Common questions
- How is my star sign worked out?
- From where the sun sat along the ecliptic on your birth date, divided into twelve equal 30° segments. Western astrology measures this from the March equinox.
- Why do the dates vary between sources?
- Because the equinox does not occur at the same moment each year, boundaries can shift by about a day. Sources that round differently disagree at the edges.
- What is the deal with Ophiuchus?
- The sun does pass through it, and the IAU included it when it drew constellation boundaries in 1930. Neither the tropical nor the sidereal zodiac uses it, so no sign changed — the story resurfaces every few years regardless.
- Why is my Vedic sign different?
- Vedic astrology uses the sidereal zodiac, tied to the constellations rather than the equinox. Precession has separated the two systems by roughly 24°, close to a full sign.
- What does it mean to be born on a cusp?
- Colloquially, near a boundary. Astrologically there is no in-between state — the sun's exact position at your birth time places you in one sign or the other.
- Is there scientific evidence for astrology?
- No. Controlled studies, including large blind tests, have not found that astrological placements predict personality or life outcomes.
- Why do horoscopes feel accurate then?
- The Barnum effect: broadly worded descriptions that could apply to almost anyone are read as personally specific, and we remember the hits far better than the misses.
- What is the difference between a sun sign and a rising sign?
- The sun sign comes from the date; the rising sign is the constellation on the eastern horizon at the moment of birth, so it needs an exact time and place and changes roughly every two hours.