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Moon Phase Calculator

Find the moon phase, illumination and age for any date, plus the upcoming new and full moons.

The moon phase depends on how far through the 29.53-day synodic month a date falls, measured from a known new moon. This calculator gives the phase name, the illuminated percentage, the moon's age in days, and the dates of the next new and full moons.

Runs in your browser
Privacy
Runs entirely in your browser — nothing is uploaded
Cost
Free, unlimited, no sign-up

Frequently asked questions

Why is the moon sometimes visible in daylight?

Because its position relative to the sun, not its brightness, determines when it is up. Around first and last quarter the moon is roughly 90 degrees from the sun, which puts it in the daytime sky for half its orbit.

How to use the moon phase calculator

  1. 1Enter or paste your date.
  2. 2Set the show the next.
  3. 3The result appears immediately — copy or download it.

Embed this tool

Put the working moon phase calculator on your own site. It runs in your visitors' browsers exactly as it does here — free, no account, nothing uploaded.

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