Moon Phase Calculator

About Moon Phase Calculator

Find moon phase and illumination for a date.

How to Use

Find moon phase and illumination for a date. Enter the Date values and review the Phase name, Illumination, and Phase outputs after you calculate.

  1. Open the calculator : Use Moon Phase Calculator from the Time category.
  2. Check the inputs : Review the required values and any optional settings.
  3. Read the formula : Use the formula and notes below to understand how the result is produced.

Common Questions

What does the Moon Phase Calculator estimate?

It estimates the moon phase and illumination for a chosen date.

What can change the result?

The date and the underlying astronomical algorithm control the phase estimate.

Inputs

  • Date

Outputs

  • Phase name
  • Illumination
  • Phase