Birth Moon Phase Finder
See which phase the Moon was in on your birthday, how much of it was lit, and what tradition says about it.
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How the Phase Is Worked Out
A moon phase is the angle between the Sun and the Moon as seen from Earth. When the two are in the same direction, the Moon is new and its lit face points away from us. When they are opposite, it is full. In between, the Moon waxes, or grows, until full and then wanes. The tool computes the Sun's and Moon's positions for your birth date and works out the angle and the fraction of the face that is lit.
A full cycle takes about 29.5 days, which is why months have the length they do. The eight named phases each cover roughly a quarter of that angle for the four main phases and the stretches between them for the four intermediate ones.
Moon Phase Is Not Moon Sign
They are often confused. Your Moon sign is where in the zodiac the Moon was. Your Moon phase is how lit it was. They change on different clocks: the sign every two to three days and the phase over a month. Astrologers who use birth phases, following the work of Dane Rudhyar in the 1960s, treat it as describing the rhythm of how you express yourself.
Accuracy and Edge Cases
The tool uses noon Universal Time for your date. If your birthday falls close to the turn of a phase, the exact hour and time zone could move you to the neighboring one, and the page tells you when this is possible. For a precise answer you need your birth time, which the Birth Chart Studio uses, and which also gives you the Moon's sign.
Frequently Asked Questions
Is this my Moon sign? No, it is the phase. The tool also shows the Moon's sign at midday, and the Birth Chart Studio gives the exact sign from your birth time. Why is my phase between two names? Phases blend into each other, so the tool picks the nearest one and tells you when you are close to a boundary. Does time of day matter? It can, especially near a new or full moon.