Moon Phase Calculator
Find the current moon phase and phases for any date. Free moon phase tracker with illumination percentage.
Astronomical calculation based on the synodic month of 29.53 days. Times are approximate.
Frequently asked questions
- How is the moon phase calculated?
- From the number of days since a known new moon (January 6, 2000), divided by the 29.53-day synodic month.
- What does illumination percentage mean?
- The fraction of the moon's visible disc that is lit by the sun. Full moon is 100%, new moon 0%.
- When is the next full moon?
- The tool shows the date of the next full moon, which occurs about every 29.5 days.
- Is it accurate everywhere?
- The phase is the same worldwide on a given date. Local rising and setting times depend on your location.
This tool runs entirely in your browser. No data is uploaded anywhere.