Guide
Your Moon sign: what it shows and how it's calculated
What is a Moon sign?
Your Moon sign is the zodiac sign the Moon occupied at the moment you were born. Where the Sun sign describes your core identity and what you consciously aim for, the Moon describes the inner, instinctive layer: your emotional needs, the reactions that come before thought and what makes you feel at home.
Two people with the same Sun sign but different Moon signs can experience feelings very differently – one needs space to process them, the other wants to talk them through straight away. That's why the Moon is one of the first placements astrologers look at, together with the Sun and the Ascendant.
Moon sign vs Sun sign
The Sun spends about a month in each sign, so your Sun sign follows almost directly from your birthday. The Moon is much faster: it circles the whole zodiac in about 27⅓ days and stays in each sign for only a little over two days on average. So your birthday alone can't answer "What is my Moon sign?" – you need the Moon's actual position on that date, which is exactly what this calculator computes.
Do I need my birth time?
Often not. The Moon moves about 13 degrees a day, so on most days it stays in one sign from midnight to midnight and the date alone gives a certain answer. But it changes sign on more than 40% of days. On such a day we show both possible signs and the exact local time the Moon crossed into the next one; if you know roughly when you were born, that's usually enough to decide.
The birthplace matters for the same reason: it tells us which time zone and calendar day applied. If you leave it out, we use your device's time zone, which is right for most people born in the country where they live.
The Moon phase you were born under
Besides the sign, the result shows the lunar phase at your birth – from New Moon to Full Moon and back – and how much of the Moon's disc was lit. In astrological symbolism the phase adds another layer to the Moon sign: a waxing Moon is associated with building and momentum, a waning Moon with reflection and release.
How we calculate your Moon sign
We compute the Moon's apparent geocentric position in the tropical zodiac with the same ephemeris that powers our birth chart calculator and that we test against NASA JPL Horizons reference data. The exact moment the Moon changes sign is found to within a second, then converted to your birthplace's historical local time, including daylight saving time.