Moon phase for any date and time: the phase name, percentage illuminated and moon age in days, with the dates of the next new and full moons.
By AdminDrafted with AI writing toolsUpdated Checked examples: 5
At 21:00 on Thu 12 Nov 2026, UTC time, the Moon's phase is waxing crescent, 12% lit and 3.6 days past new. The next full moon is Tue 24 Nov 2026 14:53 (UTC+00:00) and the next new moon Wed 9 Dec 2026 00:51 (UTC+00:00).
New moon at Mon 9 Nov 2026 07:02 (UTC+00:00), so the Moon is 3.58 days old.
Σ_p denotes the periodic and planetary corrections in Meeus ch. 49; ΔT = TT − UT is taken as 69 s. All 50 USNO phase times for 2026 are matched within 0.8 minutes.
Meeus eq. 48.4 (low-precision phase angle). The idealised curve in the chart ignores the Moon's elliptical orbit.
The Moon's phase follows from two things: the time since the last true new moon (its age) and the phase angle between the Sun and Earth as seen from the Moon, which sets the lit fraction k = (1 + cos i)/2. New, quarter and full moon instants come from Jean Meeus's lunar series, which reproduce all 50 US Naval Observatory phase times for 2026 to within 0.8 minutes.
Observers, photographers and anglers use it to plan around dark skies or a full moon. At 12:00 UT on 15 January 2026 the Moon was a waning crescent, 10% lit and 26.43 days old, with the next new moon 3.33 days away.
A phase name covers 12 hours either side of the exact instant, so a calendar that labels whole days can differ by one day. Times are shown in the zone you pick, and the Southern Hemisphere option mirrors which side of the disk is lit.
The phase depends on where the instant falls between the exact new, first-quarter, full and last-quarter moons of the 29.53-day cycle. The lit fraction is k = (1 + cos i) ÷ 2, where i is the Sun–Moon phase angle. At 12:00 UTC on 15 January 2026 the Moon was a waning crescent, 10.3% lit and 26.43 days old.
Because the instant alone sets the phase, it is the same worldwide at a given moment. What changes from place to place is the local date and clock time of each new or full moon.
Four principal phases are exact instants. Between them come four stages that last several days each:
The principal phases average 7.38 days apart. Each principal name covers the 24 hours from 12 hours before its instant to 12 hours after; the rest of the cycle carries a crescent or gibbous name.
Percent illuminated is the share of the visible disk lit by the Sun. A quarter moon is about half lit, because "quarter" means a quarter of the orbit, not of the disk.
At 12:00 UTC on 26 January 2026, 7.2 hours after first quarter, 53.7% of the disk was lit. The lit share passes 50% within hours of each quarter.
Moon age is the time since the previous new moon, in days and fractions of a day. It restarts at zero at each new moon and reaches 29.3 to 29.8 days before the next one.
Waxing means the lit part is growing, from new moon to full. Waning means it is shrinking, from full back to new.
| Instant, 12:00 UTC | Phase | Illuminated % | Age days |
|---|---|---|---|
| 3 Jan 2026 | Full moon | 100.0 | 14.43 |
| 10 Jan 2026 | Last quarter | 51.6 | 21.43 |
| 15 Jan 2026 | Waning crescent | 10.3 | 26.43 |
| 18 Jan 2026 | New moon | 0.1 | 29.43 |
| 22 Jan 2026 | Waxing crescent | 13.8 | 3.67 |
The 18 January row is named new moon although the exact new moon came at 19:52 UTC, almost eight hours later. Its age of 29.43 days still counts from the previous new moon, on 20 December 2025.
By 22 January the count had restarted at the new moon of 18 January. The 10 January row reads 51.6%, not 50%, because noon came about four hours before the exact last quarter.
A full or new moon is a single instant, so its calendar date depends on the time zone. The full moon at 22:09 UTC on 1 February 2026 fell at 17:09 on 1 February in New York, but at 03:39 on 2 February in India and 07:09 on 2 February in Japan.
Naming adds a second source of difference. A calendar that marks only the date containing the exact instant shows one full-moon day, while a 24-hour naming window often spans two dates.
The US Naval Observatory's phase tables list times in Universal Time, so compare them with results in UTC.
Phase says nothing about whether the Moon is above your horizon. As a rough guide:
North of the equator a waxing Moon is lit on the right; south of the equator the view is mirrored, lit on the left. Exact moonrise and moonset times depend on where you are and the date.
Phase instants come from Jean Meeus's lunar series in Astronomical Algorithms (2nd ed., 1998, ch. 49), and the lit fraction from his phase-angle method (ch. 48).
With TT − UT fixed at 69 seconds, the series reproduces all 50 US Naval Observatory phase times for 2026 within 0.8 minutes. Times are shown to the minute.
The 69-second correction is the value for the 2020s. It was different in past centuries, so phase times for distant dates are less exact.
For sunrise, sunset and day length, use the sunrise and sunset calculator. To read a phase time on another city's clock, use the time zone converter.
Checked against: USNO API: full moon 2026-03-03 11:38 UT, 100% illuminated at noon; previous new moon 2026-02-17 12:01 UT → age 13.999 days
Checked against: USNO API: 10% illuminated at 12:00 UT; new moons 2025-12-20 01:43 and 2026-01-18 19:52 UT, full moon 2026-02-01 22:09 UT
Checked against: USNO API: new moon 2026-08-12 17:37 UT, 0% illuminated; previous new moon 2026-07-14 09:43 UT → age 29.095 days
Checked against: USNO API: first quarter 2026-01-26 04:47 UT (7.2 h earlier), 54% illuminated at noon; new moon 2026-01-18 19:52 UT → age 7.672 days
The mean synodic month, from one new moon to the next, is 29.530589 days, about 29 days 12 hours 44 minutes. Single lunations vary because the Moon's orbit is elliptical: the same Meeus series used here gives lengths between 29.27 and 29.83 days for every lunation from 1900 to 2100.
The full moon is a single instant, so its calendar date depends on the time zone. The full moon of December 2026 is at 01:28 UT on 24 December (USNO), which is still 23 December at 20:28 in New York. Enter your own time zone to see the date and time that apply where you are.
The common definition is the second full moon in one calendar month, which happens because the 29.5-day lunar cycle is shorter than most months. 31 May 2026 was one: USNO lists full moons at 17:23 UT on 1 May and 08:45 UT on 31 May. The older almanac definition is the third of four full moons in an astronomical season.
It is waxing from new moon to full moon, when the lit fraction grows each night, and waning from full back to new. Each half lasts about 14.8 days on average. In the Northern Hemisphere a waxing moon is lit on the right; south of the equator the picture is mirrored, so it is lit on the left.
About 50%. The name refers to the Moon having travelled a quarter of its orbit since new moon, not to the lit area. The lit fraction passes 50% within hours of first and last quarter: at 12:00 UT on 26 January 2026, 7.2 hours after first quarter, it was 54% (USNO).
This calculator includes 5 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.