Was the Moon full, new or somewhere in between on the day you were born? Enter your date of birth above and you will get the Moon phase for that day, with the illuminated percentage, the Moon's age in days and the next full and new moon. It works for any date from 1900 to 2100, so you can also check birthdays of parents, grandparents, children or a wedding date.
How the Moon phase is calculated
The Moon takes an average of 29.53 days to go from one new moon to the next, a period called the synodic month. To find the phase on a given day, the page first computes the exact instants of the surrounding new moons using the astronomical formulas of Jean Meeus (Astronomical Algorithms), the same method used by almanacs. The fraction of the cycle that has passed since the last new moon gives the Moon's age in days, and the illuminated share of the disk is (1 − cos(2π × fraction)) / 2.
Dates are evaluated at noon Brasília time. Because the illumination changes by at most about 10 percentage points in 24 hours, the result for another hour of the same day differs only slightly. The phase name follows the usual eight-phase scheme: the four main phases (new moon, first quarter, full moon, last quarter) cover roughly one day around the exact instant, and the in-between phases fill the rest of the cycle.
The 8 Moon phases and what they mean
| Phase | Age (days) | Illumination | What you see |
|---|---|---|---|
| New Moon | 0–1.0 and 28.5–29.5 | 0–1% | The Moon sits between the Earth and the Sun and shows us its dark side. It is practically invisible in the sky, and the nights are darkest, which is ideal for stargazing. |
| Waxing Crescent | 1.0–6.4 | 1–39% | A thin lit sliver appears low in the western sky just after sunset and sets shortly after the Sun. |
| First Quarter | 6.4–8.4 | 39–61% | Half of the disk is lit, about a week after the new moon. The Moon is easy to see in the early evening and sets around midnight. |
| Waxing Gibbous | 8.4–13.8 | 61–99% | More than half of the disk is lit and the Moon already shows up in the afternoon. It stays visible most of the night, until the small hours. |
| Full Moon | 13.8–15.8 | 99–99% | The whole disk is lit: the Moon rises as the Sun sets and stays up all night. It is the brightest and most photographed phase. |
| Waning Gibbous | 15.8–21.1 | 99–61% | The lit part starts to shrink. The Moon rises a few hours after dusk and is still in the sky when day breaks. |
| Last Quarter | 21.1–23.2 | 61–39% | Half of the disk is lit again, on the opposite side from the first quarter. The Moon rises around midnight and is visible in the morning. |
| Waning Crescent | 23.2–28.5 | 39–1% | Only a thin sliver is left, visible in the east shortly before dawn, as the cycle prepares to start over with the new moon. |
Moon phases on famous dates
Click a date to open the full page for that day.
| Date | Event | Moon phase | Illumination |
|---|---|---|---|
| July 20, 1969 | First Moon landing (Apollo 11) | 🌒 Waxing Crescent | 36% |
| June 21, 1970 | Brazil win their third World Cup | 🌖 Waning Gibbous | 92% |
| November 9, 1989 | Fall of the Berlin Wall | 🌔 Waxing Gibbous | 84% |
| July 17, 1994 | Brazil win their fourth World Cup | 🌔 Waxing Gibbous | 64% |
| January 1, 2000 | First day of the year 2000 | 🌘 Waning Crescent | 27% |
| June 30, 2002 | Brazil win their fifth World Cup | 🌖 Waning Gibbous | 75% |
| October 2, 2026 | Today | 🌗 Last Quarter | 57% |
What can you do with the Moon phase of a birthday?
Most people look it up out of curiosity, to say "I was born under a full moon" or to compare with siblings and friends. Photographers and event planners use the same date lookup to plan shoots, weddings and outdoor events around a bright or a dark night. Folklore and astrology attach meanings to the phase of birth, but science has found no effect on personality or health, so treat it as a fun fact.
Remember that the Moon's phase is the same everywhere on Earth at a given moment; only the way it looks (which side is lit) depends on the hemisphere. For the phase right now and the next new and full moons, see the Moon phase today page. You can also find out which day of the week you were born on, or count the days between two dates to know exactly how many days old you are.