Your Moon sign is the zodiac sign the Moon occupied at the time you were born. The Moon moves through a sign in about 2.5 days, so the date alone is often enough, and the time matters only when the Moon changed sign that day. A person born on 1 January 2000 at 12:00 in London has a Moon in Scorpio.
What is a Moon sign?
In astrology, the Moon sign is said to describe your emotional life, instincts and what makes you feel secure, in contrast to the Sun sign, which stands for core identity. The Moon is the fastest moving body in the chart, circling the zodiac in about 27.3 days and spending roughly 2.3 to 2.5 days in each sign. Two people born on the same day can therefore have Moon signs that differ by one or two signs, and the exact time sometimes decides it.
The calculator gives your Moon’s sign and position in degrees, along with the Sun and rising sign so you have the three main placements together.
How the calculation works
Your birth chart is a snapshot of the sky at the moment and place you were born. The tool converts your local birth time to universal time using the time-zone rules for the date (including daylight saving), calculates the Julian date and then uses published low-precision formulas: the Sun’s position from its mean longitude and equation of centre, and the Moon’s position from a series of the largest periodic terms. The Ascendant comes from the local sidereal time and your latitude. Signs are in the tropical zodiac, as used in Western astrology.
Accuracy and limits
- The Sun and Moon are accurate to about a third of a degree, enough for the sign unless you were born within the first or last degree of one.
- The Ascendant moves through all twelve signs every 24 hours, around one degree every four minutes. An error of 15 minutes in birth time can move it a few degrees, and sometimes into the next sign.
- Extreme latitudes (above about 66°) have no stable Ascendant calculation.
- Birth times on certificates may be rounded, so astrologers often “rectify” a chart against life events.
If you only know your approximate birth time, try the calculation for the start and end of the window. If the sign is the same, you are probably safe.
The Moon matters in other cultures too: the Hindu nakshatra system and lunar calendars used for festivals in many countries rely on the Moon’s position. For the rising sign see the rising sign calculator, and for the lunar-based Chinese calendar the Chinese zodiac calculator.
How to use this calculator
- Enter your date and time of birth.
- Select your place of birth for the correct time zone.
- Read your Moon sign, with the Sun and rising sign as extras.
- Check again with the earliest and latest possible time if you are near a sign change.
Key figures at a glance
| Moon in a sign | About 2.5 days |
|---|---|
| Full circuit | About 27.3 days |
| Precision | About 0.3° |
| Zodiac | Tropical |
Frequently asked questions
For the rising sign, yes: it changes about every two hours. For the Moon, the exact time matters less, except on days when it changes sign.
Choose the place of birth. The tool applies the historical time-zone and daylight-saving rules of that place.
Sun and Moon are accurate to a fraction of a degree. The Ascendant is accurate to about one degree if the time and place are correct.
The tropical zodiac, standard in Western astrology.
The positions are astronomy. The claims about personality are not supported by evidence.