Moon Phase Calculator
Find the moon's phase and age on any date from 1900 to 2100, and when the next full moon and new moon fall, in your own UTC offset.
Result
Phase: Waxing gibbousEstimate
Phase times are accurate to about a minute. A principal phase names the whole local date it falls on.
- Days since the new moon
- 14.4Estimate
- Next full moon
- September 26, 2026Estimate
- Next full moon, time
- 4:49 PMEstimate
- Next new moon
- October 10, 2026Estimate
- Next new moon, time
- 3:50 PMEstimate
https://calcgallery.com/date-time/moon-phase-calculator/
Calendar results use the proleptic Gregorian calendar. Timezone results use the IANA data supplied by your browser or server, whose political rules can change. Confirm critical schedules with the people or service involved. Read the full disclaimer
How to use the Moon Phase Calculator
- Pick a date between 1900 and 2100 and, if it matters, a time of day.
- Enter your UTC offset for that date, for example −4 for New York in summer or 5.5 for India, so the dates and times come out on your own clock.
- Read the phase, the moon's age in days, and when the next full moon and new moon fall.
How the phase times are found
Meeus’s method starts from the mean lunar month, 29.530588861 days, counted from a new moon in January 2000. For any lunation it gives the mean time of new moon, first quarter, full moon and last quarter, then corrects each with about forty periodic terms for the eccentricity of the Moon’s orbit, the Sun’s pull and the planets. The corrections move the true phase by up to about 19 hours from the mean one.
mean phase = 2451550.09766 + 29.530588861 × k (Julian ephemeris days)true phase = mean phase + periodic corrections + planetary termsk = 0 for the new moon of 6 January 2000; add 0.25, 0.5, 0.75 for the quartersThe result is in dynamical time, the uniform time scale of the orbit calculations. Clocks keep universal time, which drifts because the Earth’s rotation is slowing, so the page subtracts ΔT, a little over a minute today, using Espenak and Meeus’s published polynomials.
Naming the day
The page finds the last new moon before the moment you enter and the four phases that follow it. If one of them falls on your date, on your clock, the day takes its name. Otherwise the moon is a waxing crescent between new moon and first quarter, waxing gibbous up to full, waning gibbous down to last quarter and a waning crescent before the next new moon.
Dates the page covers
The ΔT formulas used here run from 1900 to 2150, and the page accepts dates from 1900 to 2100. Meeus’s algorithm reaches further, but outside that range the gap between the two time scales is less certain than the minute the page shows.
With your numbers
- Days since the last new moon: 14.4
- Next full moon: September 26, 2026, 4:49 PM
- Next new moon: October 10, 2026, 3:50 PM
- Phase on September 25, 2026: Waxing gibbous
Quick reference
Phase times are accurate to about a minute. A principal phase names the whole local date it falls on.
| Example | Phase |
|---|---|
| 25 September 2026, noon UTC | Waxing gibbous |
| 26 September 2026, noon UTC | Full moon |
| 26 September 2026, noon at UTC+9 | Waxing gibbous |
| 15 September 2026, 08:00 at UTC−4 | Waxing crescent |
| 4 September 2026, 20:00 at UTC+5.5 | Last quarter |
| 1 October 2026, noon UTC | Waning gibbous |
| 6 January 2000, 18:14 UTC | New moon |
| 20 July 1969, 20:17 UTC | Waxing crescent |
Common questions about the Moon Phase Calculator
- Why does the phase not depend on where I am?
- The phases are set by where the Moon is in its orbit, which is the same instant for everyone on Earth. Only the clock changes: a full moon at 16:49 UTC is 12:49 in New York and 01:49 the next morning in Tokyo. That is why the page asks for a UTC offset and not a place.
- How accurate are the times?
- The algorithm, from chapter 49 of Jean Meeus’s Astronomical Algorithms, gives phase times to within about a minute of the published ones. On this page the next full and new moon times match the US Naval Observatory’s tables to the minute for the dates checked.
- Why is a day called full moon when the moon was full at 5 a.m.?
- A full moon, like a new moon or a quarter, is an instant, not a day. Calendars and almanacs name the whole date on which that instant falls, and the page does the same in your time zone. Between the instants the page says crescent or gibbous, waxing or waning.
- What is the moon's age?
- The days since the last new moon. A lunar month, new moon to new moon, averages about 29.5 days but runs up to about 7 hours longer or shorter, because the Moon’s orbit is an ellipse that the Sun’s pull keeps changing. So an age of 15 days is not always the full moon.
- Does the page show how much of the moon is lit?
- No. The illuminated fraction needs the positions of the Moon and the Sun, which is a different and much longer calculation than the phase times. The drawing shows the shape roughly, as seen from the northern hemisphere; from the southern hemisphere it is mirrored.