Moon Phase Calculator
Pick a date to see how the Moon looked that day, how much of it was lit and when the next phases happen, in your own time zone.
How to use it
- Choose a date; today is selected at first.
- Check that the time zone is yours, since a phase can fall on different dates around the world.
- Read the phase, the illumination and the next phases, and browse the calendar of the month.
Frequently asked questions
How is the moon phase calculated?
The exact moments of the new moon, first quarter, full moon and last quarter from 1900 to 2100 come from NASA JPL DE440 ephemerides and match the US Naval Observatory to the minute. Between them, the phase is interpolated in time.
Is the moon phase the same everywhere?
Yes, the lit fraction is the same for everyone at the same moment, but the date of a phase depends on the time zone. In the Southern Hemisphere the Moon looks upside down, so the lit side is on the other side.
How long is a lunar cycle?
On average 29.53 days from one new moon to the next. Because the Moon's orbit is an ellipse, a cycle can be a few hours shorter or longer, between about 29.3 and 29.8 days.
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