The moon phase you were born under is the phase the Moon was in at the moment of your birth, and you can work it out from the angle between the Sun and Moon in your birth chart. Astrologers who use it, following the twentieth-century astrologer Dane Rudhyar, divide the cycle into eight phases of 45 degrees each, from New Moon to Balsamic, and link each one to a broad temperament: how you tend to start, build and let go. It takes about two minutes to find yours.
Finding your phase in two minutes
You need the zodiac positions of your Sun and Moon. If you don't have them, draw your chart free with our birth chart calculator; a birth time makes it more precise, but the date alone is often enough.
Next, turn each position into a number from 0 to 360, by adding the degree to the starting point of its sign:
- Aries 0, Taurus 30, Gemini 60, Cancer 90
- Leo 120, Virgo 150, Libra 180, Scorpio 210
- Sagittarius 240, Capricorn 270, Aquarius 300, Pisces 330
Then subtract the Sun's number from the Moon's. If the answer is negative, add 360. The result is how far the Moon is ahead of the Sun, and that tells you the phase.
Two worked examples
These are made-up charts.
Example one. Sun at 18 degrees Libra, so 180 plus 18 is 198. Moon at 4 degrees Capricorn, so 270 plus 4 is 274. Moon minus Sun: 274 minus 198 is 76. A result between 45 and 90 is the Crescent phase.
Example two. Sun at 10 degrees Taurus, so 30 plus 10 is 40. Moon at 2 degrees Aries, so 0 plus 2 is 2. Moon minus Sun: 2 minus 40 is -38, and -38 plus 360 is 322. A result between 315 and 360 is the Balsamic phase.
When the birth time matters
The Moon moves about half a degree an hour relative to the Sun, so if your result lands within a few degrees of a boundary, the time of day can change your phase. Without a birth time, look at both possibilities. Our moon sign calculator will also tell you whether the Moon changed sign on your birth date, which is another sign you need the time.
The eight phases at a glance
Each phase lasts about three and a half days of real time.
- New Moon: 0 to 45 degrees
- Crescent: 45 to 90
- First Quarter: 90 to 135
- Gibbous: 135 to 180
- Full Moon: 180 to 225
- Disseminating: 225 to 270
- Last Quarter: 270 to 315
- Balsamic: 315 to 360
What each phase is said to describe
These are interpretations from modern astrology, not findings. Read them the way you'd read a character sketch: some lines will fit, some won't, and your Sun, Moon and rising signs will color all of it.
New Moon (0 to 45)
Instinctive starters. People born in this phase are said to act first and reflect later, throwing themselves at whatever's in front of them. The strength is enthusiasm and the willingness to begin before the plan is finished. The struggle is following through once the novelty fades.
Crescent (45 to 90)
The phase of pushing forward against inertia. Crescent people are described as determined but often pulled back by the past: family expectations, old habits, a familiar town. Much of their energy goes into breaking free and building something of their own.
First Quarter (90 to 135)
Builders and decision makers. Astrologers associate this phase with a taste for challenge and a habit of tearing down what isn't working to make room for something sturdier. They can come across as forceful; they get things built.
Gibbous (135 to 180)
The refiners. People born in the gibbous phase are said to ask "how could this be better?" about almost everything: their work, their relationships, themselves. Careful, analytical, devoted to improvement, and sometimes hard to satisfy.
Full Moon (180 to 225)
The phase of relationship and perspective. With the Sun and Moon opposite each other, full moon people are described as seeing themselves most clearly through other people, and as feeling the pull of two sides at once. They tend to be good at seeing every angle, and less good at choosing one.
Disseminating (225 to 270)
The sharers. This phase is linked with teaching, writing, explaining, recommending: passing on what you've learned. Disseminating people often have a cause, a favorite book they press on everyone, or a talent for making complex things plain.
Last Quarter (270 to 315)
Reformers and re-thinkers. Astrologers describe this phase as a crisis of belief: people who outgrow the ideas they were raised with and rebuild their views on their own terms. Principled, independent, occasionally seen as stubborn.
Balsamic (315 to 360)
The finishers and visionaries. The last phase before the new moon is associated with endings, solitude and a strong sense of the future. Balsamic people are often described as old souls, people who complete what others started and quietly prepare for what comes next.
Why astrological phases don't match the calendar exactly
If your parents said you were born on a full moon, you might be surprised to find yourself in the Gibbous phase. That's because astronomers and astrologers use the same names differently.
To an astronomer, full moon is a single instant, the moment the Moon is exactly opposite the Sun at 180 degrees. First quarter is the moment it reaches 90 degrees. In Rudhyar's system, each name covers the 45 degrees after that moment. So someone born the evening before the exact full moon, at 176 degrees, is in the Gibbous phase astrologically, even though the Moon looked full. Someone born two days after, at about 205 degrees, is still in the Full Moon phase although the almanac would call that Moon waning gibbous.
Neither system is wrong. One describes what you see; the other divides the cycle into equal parts for interpretation. Our guide to the Moon's phases explained covers the astronomer's version, and waxing vs waning moon explains the two halves of the cycle that sit behind both.
Using your phase alongside the rest of your chart
Your birth phase is a relationship between two parts of your chart, the Sun and the Moon, so it adds most when you already know those two. In broad terms, astrologers read the Sun as what you're aiming for and the Moon as what you need to feel settled; the phase describes how those two get along. If that's new to you, start with sun, moon and rising signs explained.
Astrologers who work with phases also use the progressed lunation cycle, a technique in which the chart is moved forward symbolically, one day for each year of life. In that system, your progressed Sun and Moon go through all eight phases over roughly 29 or 30 years, spending about three and a half years in each. Many people find it a thought-provoking way to look back at the chapters of their life, whatever they make of astrology.
Questions readers ask
Does the moon phase you were born under shape your personality?
There's no scientific evidence that it does. In astrology it's used as one interpretive layer among many, and it's best treated as a prompt for reflection. If a description fits you, it can be a useful way to talk about your habits; if it doesn't, the rest of your chart and your own experience matter more.
What if I don't know my birth time?
Work out the phase using noon on your birth date. If the result is more than about six degrees from a phase boundary, your phase is almost certainly right, because the Moon only moves around six degrees relative to the Sun in half a day.
Is it special to be born on a full moon or a new moon?
In astronomical terms, not especially: full and new moons come around every month, so plenty of people are born close to one. In astrology, being born close to the exact full or new moon is sometimes read as a strong emphasis on that phase's themes, but there's no agreed rule.
Can my moon phase change during my life?
Your birth phase doesn't change. In the progressed lunation technique, a symbolic "progressed" phase moves through the cycle over about three decades, which some astrologers use to describe changing chapters of life.
