Free astrology calculator
Moon Sign Calculator
The Moon moves through a whole sign in about two and a half days, so your birth date usually settles your Moon sign. When it does not, because the Moon changed sign that day, we tell you, show both possibilities and the local time of the change.
What the Moon sign is
In astrology the Moon speaks to your emotional life: what you need in order to feel safe, how you respond when something touches you, and the habits that comfort you. Where the Sun sign is the part of you that shows up to work, the Moon sign is often described as the part that comes home. Many people who do not recognise themselves in their Sun sign find their Moon sign a closer fit.
When the Moon changes sign on your birthday
The Moon moves about 12 to 15 degrees a day, so it crosses into a new sign roughly every two and a half days. We counted every day from 1950 to 1999: on 43.9% of them the Moon changed sign at some point. If you know your birth time, that does not matter, because we calculate the Moon for the exact minute. If you do not, we check the Moon at the first and last minute of your birth date in your birthplace's local time. When the sign is the same at both ends, your Moon sign is certain. When it is not, we show both signs and the local time of the change, so a rough idea of your birth time (morning or evening) can settle it.
How we calculate it
Your birth date and time are converted to Universal Time with the historical time zone rules of your birthplace, including daylight saving time and local mean time before standard time. The Moon's position comes from Astronomy Engine, in the tropical zodiac. We test it against NASA's JPL Horizons ephemeris on thirteen documented birth charts from 1879 to 1989: every Moon position agrees within a tenth of an arcminute, and on the six birth dates where the Moon changed sign, our change time matches Horizons to the minute. More on our methodology page.
Keep exploring
The Moon is one of the big three. See it with your Sun and rising sign, find your rising sign on its own, or look at Venus, the other planet astrologers read for affection. On the numerology side, the soul urge number also looks at what you want inside.
The Moon in each sign
How older texts and today's astrologers describe the natal Moon in each of the twelve signs.
Questions people ask
You need the position of the Moon on the zodiac at the moment you were born, which takes your birth date, your birthplace (for the time zone) and ideally your birth time. The Moon spends only about two and a half days in each sign, so the date alone is usually enough, but not always: on about 44% of days the Moon changes sign at some point. Enter your details above; if you do not know your time and the Moon changed sign that day, we show both possibilities and the time the change happened.
Your Sun sign comes from where the Sun was on your birth date, and everyone born within the same month or so shares it. Your Moon sign comes from where the Moon was, and because the Moon moves about thirteen times faster, it changes every couple of days. In astrology the Sun is read as your core identity and the Moon as your emotional needs: what helps you feel safe, rested and understood. Our Sun, Moon and rising calculator shows them side by side.
Astrology does not rank Moon signs by luck. Each Moon sign describes a different emotional style, with its own comforts and its own growth edges. A site that names one Moon sign as the luckiest is giving an opinion, not a calculation.
Astrologers read the Moon as your emotional nature: what helps you feel safe, what comforts you and how you respond before you have time to think. Your Moon sign is read as the style of that. In Astrology for All (1899), for example, Alan Leo described the Moon in Gemini as making a person "a lover of books, of study, of scientific and literary pursuits". Your result gives the traditional reading and later interpretations for your sign, as a prompt for reflection rather than a prediction.
About every 2.3 days. The Moon goes once around the zodiac in about 27.3 days, according to NASA's fact sheet, and the zodiac has twelve signs, so it enters a new sign roughly thirteen times a month. That speed is why the birth time matters more for the Moon sign than it does for the Sun, Venus or Mars.
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