Moon Phase Calculator

How to use

1. 1Pick a mode at the top: Moon phase right now, Phase on a date, or All phases in a year.
2. 2Right now mode shows the current phase live (updated every minute) with a moon disk, illumination percentage, age in days, and a list of the next New, First Quarter, Full, and Last Quarter moons.
3. 3Phase on a date mode lets you enter any calendar date and time and read the same panel for that moment. Use the quick chips for Right now, In 7 days, New Year noon, or 25 years ago.
4. 4All phases in a year mode renders the full lunar calendar: every new, first quarter, full, and last quarter moon for the year, with weekdays, times, and the traditional Northern Hemisphere full moon nickname for each month.
5. 5Switch the Time zone selector between your local IANA zone and UTC. All result times use the active zone.
6. 6Click Copy report (date or now mode) or Copy year list (year mode) to copy a plain-text summary you can save, share, or paste into notes.

About this tool

Moon Phase Calculator answers the everyday questions about the moon in one place: what is the moon phase right now, what is the moon phase on a specific date, and when is the next full moon (or new moon, first quarter, or last quarter). The current-phase mode shows a live moon disk drawn entirely with SVG, the named phase (New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, or Waning Crescent), the illuminated fraction of the visible disk as a percentage, the moon's age in days since the last new moon, and the phase angle in degrees. The date mode lets you pick any date and time between 1900 and 2100 to look up the moon for a birthday, a wedding, a camping trip, a fishing outing, a photography plan, or a school project. The year mode renders the full lunar calendar for any year between 1900 and 2100, listing every new moon, first quarter, full moon, and last quarter with the date, weekday, time, and (for full moons) the traditional Northern Hemisphere Farmer's Almanac nickname (Wolf Moon in January, Snow Moon in February, Worm Moon in March, Pink Moon in April, Flower Moon in May, Strawberry Moon in June, Buck Moon in July, Sturgeon Moon in August, Harvest Moon in September, Hunter's Moon in October, Beaver Moon in November, and Cold Moon in December). The synodic age math uses the standard reference new moon at JDE 2451550.09766 (6 January 2000, 18:14 UTC) and the mean synodic month of 29.530588853 days, then computes the illuminated fraction with the half-angle formula (1 - cos(phase angle)) / 2 used in popular astronomy texts and apps. Upcoming phase dates use the Meeus chapter 49 mean-phase formula, which is accurate to within a few hours of the true phase for centuries near the present. Results display in your local time zone or in UTC. Everything runs locally in your browser; the dates you enter are never uploaded. Useful for gardening with the lunar cycle, planning landscape and astro-photography, picking dates for night hikes, fishing or hunting around the new and full moon, scheduling outdoor events around bright or dark skies, looking up the moon phase for a birthday or anniversary, and answering questions like 'is it a full moon tonight' or 'when is the next harvest moon'.

Free to use. Works in your browser. No signup, no login.