๐ Moon Phase Calculator
Enter a date to see the calculation
* This is a simplified calculation based on the average synodic month and may differ slightly from precise astronomical data.
Enter a date and calculate the moon's age (days since the last new moon), phase (new moon, first quarter, full moon, last quarter, etc.), and how much of it appears illuminated. Useful for stargazing or planning a moon-viewing event.
How to use
- Enter the date you want to check.
- The moon phase, age, and illumination percentage are shown automatically.
FAQ
How accurate is this calculation?
This is a simplified calculation based on the average synodic month (29.53 days), so it can differ from precise astronomical ephemeris data by a few hours to about a day. Use a dedicated astronomical almanac for precise observation planning.
Does this account for time zones?
This tool calculates based on noon UTC on the entered date, so the exact phase appearance may shift slightly near a date boundary.
Can I check dates in the past or future?
Yes โ since the moon's cycle is regular, this works for any date, past or future.