Moon Phase Calculator

See today's moon phase and illumination with an astronomical approximation.

Date:

How to use

Pick any date (defaults to today) and see the phase. Everything runs in your browser.

How accurate is this?

It's a standard synodic-month approximation — accurate within about a day.

What are the 8 phases?

New, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter, waning crescent.

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