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Lunar Age Calculator
Count how many full moons, new moons, and complete lunar cycles have passed between any two dates.
Try your date of birth, or any milestone.
Defaults to today.
Coming up next
Next full moon: Aug 28, 2026, 02:07 AM
Next new moon: Aug 13, 2026, 07:45 AM
Each lunar cycle — from one new moon to the next — takes about 29.53 days. Pick a starting date and an ending date below to see how many lunar months have elapsed, plus the exact count of new moons and full moons in between.
How lunar age is calculated
Elapsed days = (end date − start date). Lunar months = elapsed days ÷ 29.530588853.
Full moon count = how many times the cycle fraction crosses 0.5 in that interval. New moon count = how many times it crosses 0 (the start of a new cycle).
Example: from January 1, 2000 to January 1, 2025 is 9,131 days ≈ 309.2 lunar months ≈ 309 full moons and 309 new moons.
Solar vs lunar time
Solar year: ~365.24 days. The basis of the Gregorian calendar.
Lunar (synodic) month: ~29.53 days. The basis of the Islamic Hijri calendar — a year of 12 lunar months is ~354 days, so dates drift earlier each solar year.
Lunisolar calendars (Hebrew, Chinese, Hindu) reconcile the two by adding a 13th 'leap month' every 2–3 years to keep lunar months aligned with the seasons.
Why every cycle is slightly different
The 29.53-day synodic month is an average. The moon's orbit is elliptical, so the time between two consecutive new moons can vary by up to ±7 hours depending on where in the orbit the moon happens to be.
Over long spans those variations average out — which is why the mean synodic period gives accurate counts of full and new moons even decades into the future.
Frequently asked questions
What is lunar age?
Two things, depending on context. In moon astronomy, 'lunar age' is the moon's own age in days since the last new moon — it cycles from 0 to about 29.53. In this calculator, 'lunar age' also refers to your age (or any time span) measured in complete lunar cycles instead of solar years.
How many lunar months are in a year?
About 12.37. A solar year is 365.24 days; the synodic month is 29.53 days, so 365.24 ÷ 29.53 ≈ 12.37 lunar months. That extra 0.37 is why a purely lunar calendar (like the Islamic Hijri calendar) drifts about 11 days earlier each solar year.
How many full moons happen in a year?
Usually 12, sometimes 13. A year with 13 full moons contains a 'blue moon' — the second full moon to fall inside a single calendar month, which happens roughly every 2.5 to 3 years.
How many full moons have I seen in my lifetime?
Set the start date to your date of birth and the end date to today. The 'full moons' count is the answer. The average person sees about 12 full moons a year — so someone who is 30 has lived through roughly 370 full moons.
What is a synodic month?
The time from one new moon to the next — 29.530588853 days on average. It's longer than the sidereal month (27.32 days, the time the moon takes to orbit Earth relative to the stars) because Earth is also moving around the sun, so the moon has to catch up to the same sun-Earth-moon alignment.
Why count moons instead of years?
It's a different lens on time. Cultures with lunar calendars have measured months by moons for thousands of years, and many people find the count personally meaningful — every full moon is a noticeable event in the sky, while years are an abstraction.
How accurate are these counts?
We compute the dates of each new moon and full moon between your start and end dates using the mean synodic period of 29.530588853 days, anchored on a known reference new moon. That's accurate within a few hours, so the integer counts of full and new moons are reliable.
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