Zodiac Sign Calculator
Find your sun sign from your date of birth.
How Your Sun Sign Is Determined
Your sun sign is the zodiac sign the sun occupied at the moment you were born. The zodiac divides the ecliptic — the apparent yearly path of the sun against the stars — into twelve equal segments of thirty degrees each, and the sun moves through roughly one degree per day, completing the circuit in a year.
Because a year is not a whole number of days, the sun does not arrive at each boundary at the same time annually. It drifts later by about six hours each year, then jumps back when February gains a day. Over a four-year cycle the crossing time for any given sign can vary by nearly twenty-four hours, which is why fixed date ranges are always approximate.
This calculator computes the sun's actual position for the date you enter rather than reading from a table. For the great majority of birthdays the two methods agree. For birthdays close to a sign boundary, the year matters and an exact birth time may be needed to determine the sun's position with complete confidence.
Being Born On The Cusp
There is a persistent idea that people born near a boundary are a blend of both signs — a Leo-Virgo, or a Pisces-Aries. Astrologically this is not how it works. At any given moment the sun is in one sign or the other; there is no overlap, and no intermediate state.
What is true is that a chart can carry strong signatures from a neighboring sign for other reasons. Someone born in the last days of Leo may well have Mercury and Venus already in Virgo, since those planets travel close to the sun and frequently cross the boundary before it does. That produces a person who genuinely reads as a mix — but the mixture comes from separate placements, not from the sun being in two places at once.
If your birthday falls near a boundary, the useful next step is a full chart rather than a cusp label. It will show you exactly which of your planets sit on each side of the line.
What The Sun Sign Actually Describes
The sun in a chart describes identity and direction: the quality a person is oriented toward and generally recognized by. It is the single most visible placement, which is why it became the one everybody knows, and it is also only one of ten.
A description of a sun sign will therefore always be partly wrong about any individual. Someone with the sun in Sagittarius and the moon in Capricorn is not the restless optimist the sun sign description promises; they are someone with an optimistic outward orientation and a cautious private one, which is a different person entirely. This is the most common reason people conclude that astrology does not describe them — they are reading one twelfth of a chart and expecting the whole.
If the sun sign description here does not fit, that is informative rather than disappointing. It usually means another placement is doing more of the work, and the natal chart calculator will show you which one.
Tropical And Sidereal Zodiacs
Western astrology uses the tropical zodiac, which anchors the start of Aries to the March equinox. Vedic astrology uses the sidereal zodiac, which anchors the signs to the constellations themselves. Because the earth's axis wobbles slowly over a twenty-six-thousand-year cycle, the two systems have drifted about twenty-four degrees apart.
The practical consequence is that a tropical Leo is often a sidereal Cancer. Neither system is in error; they measure from different reference points, and each is internally consistent. This calculator uses the tropical zodiac, as does every other reading on this site. If you have seen a different sign reported for your birthday somewhere else, a sidereal calculation is the most likely explanation.
The Thirteenth Sign Question
Every few years a story circulates announcing that astrologers have forgotten a constellation and that everyone's sign has changed. The constellation is Ophiuchus, the sun does pass through it, and nothing about this is new — it has been known for as long as the zodiac has existed.
The confusion comes from treating the zodiac as a map of constellations, which it is not. The tropical zodiac divides the sun's path into twelve equal segments measured from the equinox; the constellations along that path are irregular in size, overlap the divisions untidily, and were never the basis for the measurement. A sign is a thirty-degree portion of a circle, not a picture in the sky.
So the answer is that your sign has not changed and there is no thirteenth one in the system this site uses. The story returns periodically because it is a good headline, not because anything has been discovered.
After You Have Your Sign
A sun sign is a reasonable place to start reading and a poor place to stop. The next two placements worth knowing are the moon, which describes emotional habit and what you need in order to feel settled, and the ascendant, which describes the manner you lead with and how you come across before anyone knows you.
Those three together — sun, moon, and rising — carry most of what people recognize as a personality, and they frequently explain the gap between a sun sign description and the person reading it. Both are calculated as part of the natal chart, which needs a birth time in addition to the date this calculator uses.
From there, the sign guides on this site cover each of the twelve in depth: temperament, compatibility, the element and modality behind them, and how the sign behaves when it is under pressure rather than at its best. That last part is usually the most informative, and it is the part a one-line horoscope never has room for.