Moon phase today

Understanding the Moon

One cycle, many shapes

Waxing means the lit portion is growing; waning means it is shrinking. The phase is shared worldwide, though its orientation in your sky varies. These illustrations show the Northern Hemisphere orientation.

Upcoming phase dates are estimates and can differ from astronomical dates by a day or more. This model uses a 29.53059-day average cycle from the new moon on 6 January 2000 at 18:14 UTC. The Moon’s uneven orbital speed limits this simple model: illumination is approximate and has no guaranteed error bound. Moon age is the number of days into this model’s cycle.

Today’s phase uses the current instant, while each calendar date is sampled at noon in your browser’s local timezone. These different sampling times can produce different illumination values or phase names for the same date. Changing the calendar month or year changes the calendar; today’s phase and the upcoming phases remain relative to now.

Phase names are assigned to the nearest eighth of the model’s cycle. The upcoming list instead calculates the next strictly future new moon, first quarter, full moon and last quarter in the model, ordered by time. A displayed Full moon label therefore does not identify the exact astronomical full-moon instant, and the upcoming list’s dates remain estimates.

All moon calculations run on your device, with no lunar data service or location needed. Learn about moon phases at the US Naval Observatory.