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A DIFFERENT WAY TO COUNT

Full Moons Since Birth Calculator

Your life has unfolded under a changing Moon. Count the actual full-moon instants since your starting date, rather than dividing your age by an average lunar month.

MAKE IT PERSONAL

Start with your date.

Choose a date and the time zone where your story began.

Default: 12:00 noon.

Uses shared site-wide tab-session storage when available. Your browser may restore closed sessions. Clear date removes the saved selection from all calculators. Nothing is sent to our server.

THE CALCULATION

How it works

We calculate geocentric full moons with Jean Meeus’s true-phase algorithm: mean phase plus periodic and planetary corrections, then an Espenak–Meeus ΔT conversion to approximate UTC. A phase at the starting instant is excluded; a phase exactly at the counting endpoint is included.

A worked example

For a start of 1 January 2000 at 00:00 UTC, the first full moon afterwards was on 21 January 2000 at about 04:40 UTC. The worked count below stops at 1 January 2025 at 00:00 UTC, so it remains reproducible as today’s date changes.

309 full moons

Strictly after 1 January 2000 at 00:00 UTC, through 1 January 2025 at 00:00 UTC.

Why mark this moment?

A hundred full moons is a little over eight years. Unlike a repeating calendar date, the phase wanders through the months, making a lunar anniversary a different way to reflect on time.

Precision & limitations

Expected phase accuracy is a few minutes for 1900–2100; allow up to 15 minutes for 2100–2200 because future ΔT is uncertain. The default starting time is 12:00 noon. Changing it to a documented time can include or exclude a full moon on the starting day. This counts global phase instants, not local moonrises or visibility.

Input dates are supported from 1900 to 2100, up to today. Astronomical events are shown only through 2200. Explore the full Starry Moments calendar.