Moon Phase Calculator
See the moon phase for any date — phase name, illumination percentage, moon age and a visual moon, plus the next full and new moon dates.
About the Moon Phase Calculator
Pick any date — past, present or future — and this moon phase calculator shows exactly what the moon looks like: the phase name (from New Moon through Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon and back down), the illumination percentage, and the moon's age in days since the last new moon, all illustrated with an accurately shaded moon graphic.
It also predicts the next full moon and next new moon after your chosen date — useful for planning stargazing and astrophotography sessions (new moons mean dark skies), night hikes and photography under full moonlight, fishing trips, and cultural or religious observances tied to the lunar cycle.
The math uses the mean synodic month of 29.53 days measured from a reference new moon, a standard astronomical approximation accurate to within a few hours — more than enough for planning. It runs entirely in your browser, instantly, with a copyable summary of the result.
How to Use the Moon Phase Calculator
- 1Pick a date — it defaults to today.
- 2Read the phase name, illumination percentage and moon age on the shaded moon graphic.
- 3Check the predicted next full moon and new moon dates.
- 4Copy the summary to share or save.
Frequently Asked Questions
What do the eight moon phases mean?
The cycle runs New Moon (0% lit), Waxing Crescent, First Quarter (50%, growing), Waxing Gibbous, Full Moon (100%), Waning Gibbous, Last Quarter (50%, shrinking), and Waning Crescent before returning to new. 'Waxing' means the lit portion grows each night; 'waning' means it shrinks.
What is the moon's age?
The number of days elapsed since the most recent new moon, running from 0 to about 29.5. Age 7.4 is first quarter, 14.8 is full, and 22.1 is last quarter. It's the standard way astronomers describe where the moon is within its cycle.
How accurate is this calculator?
It uses the mean synodic month (29.53059 days) from a known reference new moon, which lands within a few hours of precise astronomical almanac times. The real cycle varies slightly (±13 hours) because of the moon's elliptical orbit, so on boundary days the named phase could differ from an observatory's — for planning purposes it's effectively exact.
Why does the moon look flipped in the southern hemisphere?
Observers south of the equator see the moon 'upside down' relative to northern viewers, so a waxing moon lit on the right in this tool's graphic appears lit on the left from Australia or South Africa. The phase name, age and illumination percentage are identical everywhere on Earth.
When is the best moon phase for stargazing?
Around the new moon, when moonlight is minimal and faint objects like the Milky Way, nebulae and meteor showers show best. Use the next-new-moon prediction to plan dark-sky trips; conversely, the days around full moon are ideal for moonlit landscape photography and night hikes.