Lunar Calendar Calculator

A lunar calendar calculator determines the moon\. Use this calculator for accurate, instant results.

The calculator uses the standard published formula for lunar calendar. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches, percentages. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Days elapsed since reference mod 29.53 = phase day. Each step in the calculation is shown so you can verify the result manually.