Moon Sign Calculator | What Is My Moon Sign?

Moon Sign Calculator

This calculator finds the zodiac sign the Moon occupied at the moment you were born, based on your birth date, time, and city. Unlike your Sun sign, which only needs a birth date, the Moon sign relies on the Moon's much faster movement, so it needs your birth time and city as well. Alongside the Moon sign, it shows the Moon's phase on that date, from new moon to waning crescent.

How the Moon sign is calculated

Your birth date and time are converted to Coordinated Universal Time using the timezone of the city you enter. The Moon crosses roughly 13 degrees of the zodiac per day, compared to about 1 degree for the Sun, so it changes sign roughly every two days and seven hours, and even an hour's difference can shift the result. Counting forward in hours from a fixed reference point of 1 January 1900, 00:00 UTC, the calculator divides the total by the Moon's sidereal period of 27.321661 days, split into twelve equal segments of about 2.28 days (54.6 hours) each, one per zodiac sign in the standard order from Aries to Pisces. The reference point itself is calibrated to the start of the Capricorn segment, and every birth moment is placed into one of the twelve segments counted onward from that fixed point. This is a fixed-cycle approximation rather than a live ephemeris lookup, so a result near a sign boundary can differ by one sign from tools that reference full astronomical tables. Treat the result as an entertainment reference rather than a precise astrological reading.

Worked example

For a birth on 15 June 1990 at 2:30 PM in New York, Eastern Daylight Time (UTC-4), the calculator first converts the time to 18:30 UTC on the same day. That moment falls about 33,038 days, or roughly 792,906 hours, after the 1 January 1900 reference point. Dividing by the 27.321661-day cycle places the Moon in Pisces at birth. The same birth moment falls about 22.6 days into the 29.53-day phase cycle since the previous new moon, which the calculation reads as a Last Quarter Moon.

Moon phases in the cycle

The phase shown next to your Moon sign comes from a separate 29.53058868-day synodic month, counted from the same reference date and split into eight named phases. If your birth moment falls close to one of the boundaries below, treat the phase as approximate rather than exact: