Moon Phase Calculator
See the moon phase for any date: a drawn moon disc, illumination percentage, lunar age and the traditional meaning of the phase.
Result
The moon cycles through its phases every 29.53 days — the synodic month — moving from new moon through the waxing crescent, first quarter and waxing gibbous to full moon, and back through the waning phases to new again.
This calculator computes the lunar age for any date from a reference new moon using the mean synodic month, then derives the phase, the illuminated percentage of the disc and a drawing of how the moon looks on that night. The mean-cycle method is accurate to within a day, which is exactly the precision moon lore operates at.
Each phase comes with its traditional folk meaning — new moons for intentions, the waxing moon for growth, the full moon for culmination and the waning moon for release — the framework used by lunar calendars and planting almanacs for centuries.
Everything is computed locally in your browser; no dates leave your device. Handy for planning a hike under a bright moon, checking the moon of your birth date, or timing anything you like to time by the sky.