Find the moon phase for today or any date — new, full or quarter — plus the illuminated percent, the Moon’s age and the days to the next full and new moon.
Choose the date
Pick any date to see the Moon phase on that day; today is the default.
Mean synodic model — accurate to under a day for the phase, illumination and Moon age.
Moon phase, computed astronomically. The Moon’s age, illuminated percent and phase come from the chosen date using the mean synodic month. Everything runs in your browser, no account, no data sent.
The phase comes from the days since the last new moon, relative to the synodic month (29.53 days); illumination follows from the Sun–Moon angle:
On 3 January 2026, the Moon is full (100% lit). Pick another date to see the phase and the days to the next full or new moon.
From the days elapsed since a known new moon, relative to the mean synodic month (29.53 days). The position in this cycle gives the phase, and the illuminated percent follows from the Sun–Moon angle.
It is the period between two consecutive new moons, on average 29.53 days. It defines the full cycle of Moon phases, from new moon to new moon.
Eight: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter and waning crescent.
It is how much of the visible lunar disc is lit by the Sun. 0% at new moon, 50% at the quarters and 100% at full moon.
The calculator shows how many days remain until the next full moon and until the next new moon, starting from the chosen date.
Because the Moon rises and sets at different times depending on its phase; near the quarters it is above the horizon during the day, so it can be visible.
It is the second full moon in a calendar month (or the fourth in a season). It is rare, hence the phrase "once in a blue moon".