Any date
Moon Phase Calculator
Illumination of the near side
The moon phase calculator returns the U.S. phase name and the sunlit percent at local noon for the date you enter, with a Northern Hemisphere disc.
This figure is an estimate for learning and curiosity. It is not an observatory ephemeris, and it is not a guide for navigation.
How this is calculated
The same elongation model as the home page is evaluated at local noon on the date you enter. Illumination is (1 + cos i) / 2. Moon age is the span from the previous new-moon crossing to that noon, against a mean synodic month of 29.530588853 days.
Questions
What happens if the date is outside 1900–2100?
The calculator stops and explains the range. It does not invent a phase for a year it does not cover.
Is noon the same as the moment of full moon?
No. A full moon can fall at any clock time. This page reports the disc at local noon. For the instant of the next full or new moon, use the next-full-moon tool.
Which time zone is “local noon”?
Noon on this device. The IANA name you see, such as Europe/Warsaw or America/New_York, comes from the computer or phone Settings app. The page does not detect New York from your IP.
Does a date in Australia flip the disc?
No. The picture stays a Northern Hemisphere view, and the page says so. The numbers do not depend on a street address.
Can I use this for tides or sailing?
No. The figure is not a tide table and not a navigation almanac.