Moon Phase Calculator
See the moon phase for today or any date: how much of the Moon is lit, its age, and when the next full moon and new moon will be. Includes a month calendar of phases.
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Next phases
Times are shown in your local time zone and are accurate to within about an hour.
How to find the moon phase for a date
- The calculator opens on today’s date. Pick any other date, past or future, to see its moon phase.
- Read the phase name, the percentage of the Moon that is lit, and its age in days since the last new moon.
- Check the next phases list for upcoming full and new moons, or tap a day in the calendar.
The eight phases of the Moon
The Moon takes about 29.5 days to go from one new moon to the next, a period called a lunar month. At new moon it sits between Earth and the Sun and its sunlit side faces away from us. Over the following week a growing waxing crescent appears in the evening sky, reaching first quarter (half lit) about 7 days in. The waxing gibbous phase leads to the full moon around day 15, when the whole face is lit and the Moon rises at sunset. It then shrinks through waning gibbous, last quarter and waning crescent, visible in the early morning, before the next new moon.
How it is calculated
The calculator works out the positions of the Sun and Moon for the chosen moment using the standard astronomical formulas from Jean Meeus’s Astronomical Algorithms. The angle between them gives the phase and the illuminated fraction, and the exact times of the next principal phases are found by solving for when that angle reaches 0°, 90°, 180° and 270°. Results are accurate to within about an hour, which is plenty for planning.
In the Southern Hemisphere the Moon appears upside down compared with the Northern Hemisphere, so a waxing moon is lit on the left. Tick "Southern hemisphere view" to draw it that way. The phase and dates are the same everywhere on Earth; only the local time and the view change.
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Frequently asked questions
When is the next full moon?
It is listed under "Next phases" for the date you choose, with the time in your own time zone.
What does moon age mean?
The number of days since the last new moon. About 7.4 days is first quarter, 14.8 days is full moon and 22 days is last quarter.
Is the moon phase the same everywhere?
Yes. Everyone sees the same phase at the same moment, though the date and time differ by time zone, and the Moon looks flipped in the Southern Hemisphere.
How accurate is it?
Phase times are within about an hour, and the illuminated percentage within about one percent.
Is anything sent to a server?
No. Everything is calculated in your browser, and nothing you enter leaves your device.