Moon Phase Calculator
What phase is the moon in?
The phase for any date, drawn as well as named, with the illuminated fraction, the moon's age in days, and the dates of the next new and full moons.
Questions people ask
The things that come up about moon phase calculators, answered plainly.
How long is a lunar month?
29.53 days on average — the synodic month, from one new moon to the next. Individual months vary by up to 13 hours either side, because the moon's orbit is elliptical and the Earth is moving around the sun at a changing rate.
What was the moon phase on the day I was born?
Enter the date and the page draws it. Any date from well before 1900 to well after 2100 works. The named phase and the illuminated percentage are reliable across that span; the exact minute a new or full moon falls is good to about an hour, which is the limit of the truncated series behind it.
Why is the full moon not always exactly half a month after the new moon?
Same reason — an elliptical orbit. The moon moves faster near perigee, so the quarters are not evenly spaced through the month.
Related tools
Sunrise, sunset, the golden hour and the phase of the moon, anywhere on Earth.