Moon phase birthday calculator
What phase of the Moon were you born in? Enter your birthday to see it.
A date alone is checked at 12:00 UTC.
The phase repeats every 29.5 days
The date is enough for the phase name. Add a time and place if you know them: on the day of a new, quarter or full moon the exact minute can change the answer.
The Moon's phase is the angle between the Moon and the Sun as seen from Earth. It runs through eight named phases in about 29.5 days, so the phase on the day you were born is a fixed part of your birth sky, like your Sun sign. The date alone is enough for the phase. A time and place sharpen the lit percentage.
How this is calculated
The angle
The phase comes from the difference between the geocentric ecliptic longitudes of the Moon and the Sun, calculated with Astronomy Engine. 0 degrees is a new moon, 90 is first quarter, 180 is full and 270 is last quarter. The lit percentage is the share of the disc lit by the Sun, as seen from Earth.
The phase name
New moon, first quarter, full moon and last quarter are exact moments. The result uses one of those names when the moment checked is within 12 hours of it, which gives each one a window of one day. The rest of the cycle is a crescent or a gibbous Moon: waxing before the full moon, waning after it.
The moment
With a date only, the phase is checked at 12:00 UTC on that date. Add a place and it is checked at noon local time there; add a time as well and it is checked at that minute, using the IANA time zone in force in that city on that date.
Why the Moon has phases
The Moon makes no light of its own. The Sun always lights half of it, and the phase is how much of that lit half faces Earth. At a new moon the lit half faces away from us; at a full moon it faces us completely. The cycle from one new moon to the next takes about 29.5 days, a little longer than the 27.3 days the Moon takes to circle Earth, because Earth moves along its own orbit in the meantime.
Because the phase repeats every month, the phase you were born under is shared with everyone born near the same point of any lunar cycle. The sign the Moon was in is a separate thing, found with the Moon sign calculator.
The eight moon phases and what they mean in astrology
Astrologers read the birth moon phase as a temperament: where you were in the Sun and Moon's monthly cycle says something about how you start, build and let go of things. The short readings below follow that tradition and are written for entertainment.
New moon
A new moon birth is read as a start from scratch. You tend to act on instinct before you can explain it, and you often learn who you are by trying things rather than by planning them. Your own sense of direction counts for more than anyone else's map, and a blank page excites you more than it scares you.
Waxing crescent
The waxing crescent is read as effort against inertia. You push past the way things have always been done, and early doubts tend to make you more determined. Momentum matters to you: once a plan is moving you rarely want to stop it, and you can carry other people along with your belief that it will work.
First quarter
The first quarter is read as the builder's test. You meet resistance head on and make decisions quickly, sometimes before the facts are all in. People born now often do their best work with a deadline in front of them, and they get restless when nothing needs fixing.
Waxing gibbous
The waxing gibbous phase is read as refinement. You look at something that is almost right and want to make it right. You ask good questions, you see the gap between a draft and the finished thing, and you can be hard on yourself about that gap. Patience with unfinished work is the skill this phase asks you to learn.
Full moon
A full moon birth is read as a life lived in relationship. You see yourself most clearly through other people, and you can feel pulled between two sides of a choice until you find a way to hold both. Your feelings tend to show on your face, and you often understand a situation best once it is out in the open.
Waning gibbous
Astrologers call this the disseminating phase and read it as the teacher's Moon. You want to pass on what you have learned, and you are at your best explaining, sharing or translating an idea for someone else. You trust an idea more once you have tested it in conversation, and you notice quickly when a message is not landing.
Last quarter
The last quarter is read as a turning point in belief. You are willing to drop a position that no longer fits, even a popular one, and you often see what needs to end before others do. Change of direction does not frighten you, though you prefer to make it quietly and on your own terms.
Waning crescent
Astrologers call this the balsamic phase and read it as an ending that prepares a beginning. You can carry a sense of finishing something larger than yourself. Solitude and rest restore you, you think in long stretches of time, and you tend to sense where things are heading before there is much evidence for it.
The phase is one thread in the birth chart. To see where the Moon sits among the other planets, open the birth chart calculator; the sample natal report shows what the full written reading covers.
Questions
What phase of the moon was I born in?
Enter your birth date in the calculator above. It gives the phase name, how much of the Moon was lit, and the dates of the principal phases just before and after your birthday. If you know your birth time and place, add them to check the exact minute.
Do I need my birth time?
Usually not. The lit share of the Moon changes by at most about 13 percent in a day, so the phase name holds all day except on the day of a new moon, quarter or full moon. On those days the birth time can move the result to the phase before or after.
What is the difference between waxing and waning?
Waxing means the lit part is growing, from the new moon to the full moon. Waning means it is shrinking, from the full moon back to the next new moon. In the northern hemisphere a waxing Moon is lit on the right and a waning Moon on the left; south of the equator it is the other way round.
Is the moon phase the same everywhere on Earth?
Yes, at the same instant. The phase depends on where the Moon and the Sun are, not on where you stand, so everyone sees the same lit share at the same moment. What changes is the local date and clock time, and which side looks lit. The picture here shows the northern hemisphere view.
Is my moon phase the same as my Moon sign?
No. The phase is the Moon's angle from the Sun. The Moon sign is the zodiac sign the Moon was in. A person born at the next full moon a month later shares your phase but has their Moon in a different sign. The Moon sign calculator on this site finds the sign.