Moon Phase Calculator
Find which of the eight moon phases any date falls in, with the approximate percentage of the disc that is lit.
Last Quarter- Moon age
- 23.8 days Days since the last new moon.
- Distance
- 378,277 km From the centre of the Earth to the centre of the Moon.
- Moon sign
- ♍ Virgo 2.0° The twelfth of the ecliptic the Moon is in (tropical zodiac), and how far into it.
- Next full moon
- Nov 24, 2026, 2:55 PM · in 21.1 days
- Next new moon
- Nov 9, 2026, 7:03 AM · in 5.8 days
| 🌑 New Moon | Nov 9, 2026, 7:03 AM |
| 🌓 First Quarter | Nov 17, 2026, 11:49 AM |
| 🌕 Full Moon | Nov 24, 2026, 2:55 PM |
| 🌗 Last Quarter | Dec 1, 2026, 6:10 AM |
The phase follows the Moon and the Sun themselves, from the periodic terms in Meeus’s Astronomical Algorithms, and lands within a few minutes of the published times of new and full moons. It is taken at the time you set — noon unless you change it — on the clock you choose.
Eight phases and the percentage lit
Pick any date — and, if you like, a time and whether it is read on your own clock or UTC — and the calculator shows which of the eight moon phases the moon is in — new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, or waning crescent — along with the approximate percentage of the disc that is lit. It is handy for planning stargazing and astrophotography, checking whether a camping trip lands near a full moon, or simply finding out what the moon looked like on your birthday. The phase name, a drawing of the moon lit as it is at that moment — the edge of the shadow drawn where it really falls, as seen from the northern hemisphere, rather than rounded to one of eight pictures — and the illumination update live as you change the date, and the page also gives the moon's age in days, the next full and new moon, and a table of the next principal phases. The “Sweep through the cycle” slider under the day buttons moves the date a day at a time through the weeks either side of today, so you can watch the moon wax and wane.
How the phase is calculated
The moon completes one cycle of phases in an average synodic month of about 29.53 days, but a single month runs shorter or longer than that, because the Moon's orbit is an ellipse the Sun keeps tugging on — so counting average months from a known new moon drifts from the real phase by up to most of a day. The tool instead works out where the Moon and the Sun actually are, from the periodic terms in Jean Meeus's Astronomical Algorithms, and the phase is the angle between them. Eight equal arcs of that angle, centred on new moon, first quarter, full moon and last quarter, give the eight names, and the lit fraction is half of one minus the cosine of the angle: 0% at new moon and 100% at full moon. The new and full moons it finds land within a few minutes of the published times. It is not a full astronomical ephemeris, but it is accurate enough to plan by.
Frequently asked questions
How accurate is the illumination percentage?
Close. The phase angle comes from Meeus's periodic terms for where the Moon and the Sun actually are, not from an average month, and the new and full moons it finds land within a few minutes of the published times. The percentage is shown to the nearest whole percent. It is enough for planning a night out or a photograph, though not a substitute for a precise astronomical ephemeris.
Which time of day does the result reflect?
Noon on the date you pick, on your own clock, unless you change it: set a Time, and a Clock of Your time zone or UTC, and the phase, the illumination and every date on the page follow that moment. The moon's phase changes gradually, so the lit percentage shifts only slightly from morning to night, but on a day when the phase changes the time decides which name you get.
When is the next full moon?
The page prints the Next full moon and Next new moon after the date and time you set, each with its date, time and how many days away it is, and a Next principal phases table gives the coming new moon, first quarter, full moon and last quarter in order. Moon age is the days since the last new moon.
Does it give the moon’s distance, or the sign it is in?
Yes. With the phase facts, “Distance” gives how far the Moon is from the Earth at the date and time you set, centre to centre, worked from the same Meeus terms as the phase, so the near and far points of its orbit show. “Moon sign” names the sign of the tropical zodiac the Moon’s longitude falls in and how many degrees into it it is — a twelfth of the ecliptic, not the constellation behind the Moon.
Can I watch the moon change over the coming weeks?
Yes. The “Sweep through the cycle” slider under the day buttons moves the date one day at a time through the weeks either side of today and says how many days before or after today you are. The moon beside the phase name is drawn for that moment — lit on the right as it waxes, seen from the northern hemisphere — rather than as the emoji for its phase; the emoji stay in the copied text and in the table of coming phases.