Western astrology · Tools

Moon sign calculator

The Moon changes sign about every two and a half days, so the Moon sign is set by the birth date; the birth time only matters on a day the Moon changes sign. Enter the date (time if you have it) to get the Moon's sign and degree.

Birthplace (required)

The birthplace sets the time zone and the horizon; this page cannot compute without it.

How it is computed

From the birth instant and the birthplace's coordinates, an astronomical ephemeris gives the apparent ecliptic positions of the Sun, Moon and eight planets; sidereal time, latitude and the obliquity of the ecliptic give the Ascendant and Midheaven. Positions are accurate to arcminutes; the Ascendant moves about 1° every 4 minutes, so its accuracy is bounded by the birth time. Houses are whole-sign: the rising sign is the first house.

Birth time and time zone

Enter the clock time at the birthplace. It is converted to UTC with the birthplace's historical time-zone rules, including past daylight-saving periods (mainland China 1986–1991, Taiwan 1979, and so on). If the birth time is approximate, read the rising sign as a range; the page flags results near a boundary.

FAQ

What if I don't know the birth time?
The page computes the Moon at 00:00 and 24:00 local time. On most days both fall in one sign and the answer is certain; on a day the Moon changes sign, both signs are listed for you to weigh against your rough birth window.

Related tools

Beyond a single lookup, the full chart

Each tool answers one question. The four pillars and luck cycles read together are the chart.

Moon sign calculator by birth date and time | DEEP ORACLE