Moon Phase Calculator
Find the Moon's phase for any date, past or future.
About this tool
Choose any date to see the Moon's phase, how much of it is lit, its age in days since the last new moon, and the dates and times of the next new moon, first quarter, full moon and last quarter. For today, it's worked out for the current moment; for other dates, for midday. Times are shown in your device's time zone.
Rather than assuming every month lasts an average 29.53 days, which can put a full moon out by more than half a day, the calculator works out the angle between the Moon and the Sun from the main terms of the Moon's and Earth's orbits (from Jean Meeus's Astronomical Algorithms). That puts the illuminated percentage within about 1% and the times of new and full moons within about half an hour of the published figures. The picture shows the Moon as seen from the northern hemisphere, lit on the right while waxing; from Australia or South Africa it appears the other way round.