Your sun sign is where the Sun stood
Your sun sign is simply the zodiac sign the Sun occupied, as seen from Earth, at the moment you were born. Over one year the Sun appears to travel through all twelve signs, spending about a month in each one.
That is why the sun sign is the placement most people know. You only need a birthday to find it, and for most dates the answer is the same no matter what time you arrived.
Why the usual date ranges are only approximate
Horoscope columns print fixed ranges such as March 21 to April 19 for Aries. Those ranges are rounded. The Sun actually enters each sign at a different hour every year, and sometimes on a different calendar day, because the calendar year and the solar year do not line up perfectly.
If your birthday falls roughly between the 18th and the 23rd of a month, you were born close to a sign change. People often call this being born on the cusp. In astrology there is no blended cusp sign: the Sun is always in one sign or the other, and the exact birth time and place decide which.
Our calculator computes the Sun's position with Astronomy Engine. We convert your local birth time to UTC using the time zone history of your birthplace, then find the Sun's longitude to within about one arcminute. The result also shows when that sign's season began and ended in your birth year.
Degrees and decans: a closer look at your sign
Each sign covers 30 degrees of the zodiac. The degree we show tells you how far the Sun had traveled into its sign, from 0 at the start to just under 30 at the end.
Astrologers traditionally split every sign into three decans of 10 degrees each. The first decan is read as the purest expression of the sign, while the second and third are linked with the other two signs of the same element. Two people with the same sun sign may relate to different shades of it depending on their decan.
Tropical signs versus the constellations
Western astrology uses the tropical zodiac, which begins at the spring equinox and divides the year into twelve equal 30-degree signs, so the signs no longer match the star patterns that share their names.
What the Sun stands for in a chart
In astrology, the Sun is linked with the core sense of self: vitality, purpose and the way a person wants to shine. It is often read as the part of you that grows stronger with age and conscious effort.
The Sun is only one piece of the picture, though. Your Moon and rising sign add emotional and outward layers, which you can see together with the Big Three calculator. For every planet at once, open a full birth chart, or read about your sign's element on the zodiac elements page.