How to Calculate Lunar Age

Use this free how to calculate lunar age to find the moon’s age in days, its phase and illumination for any date.

How the how to calculate lunar age works

Lunar age = days since the last new moon, using a synodic month of 29.53059 days from the new moon of 6 January 2000.

Frequently asked questions

How accurate is it?

Within about a day; the true moon speeds up and slows down along its orbit.

Results are estimates for general information only. They are not a substitute for professional advice where applicable. Found a mistake? Report an error.