How accurate is this lunar age calculator?

Calculations are precise to the day, accounting for leap years and varying month lengths. Results update in real-time as you enter dates.

Does it account for time zones?

Date calculations are based on calendar dates. For time-sensitive applications, consider your local time zone when interpreting results.

Can I save my calculations?

You can bookmark the page or copy the results. The tool processes everything locally in your browser for privacy.

Lunar Age Calculator

Calculate your exact age with precision using this lunar age calculator. Get detailed breakdowns in various time units.

How It Works

Enter your birth date to see your age calculated in multiple formats:

Years, months, and days
Total days lived
Total weeks
Total hours and minutes

Practical Applications

Official documents requiring exact age
Birthday celebrations and milestones
Age verification for applications
Fun facts about your life in numbers

Lunar Age

A lunar year is twelve lunar months of about 29.53 days — roughly 354 days, eleven days short of a solar year. Calendars that track the moon therefore drift against the seasons unless they insert a leap month.

Calendar	Handling
Islamic (Hijri)	Purely lunar — dates drift ~11 days earlier each solar year
Hebrew	Lunisolar — a leap month 7 times in 19 years
Chinese	Lunisolar — leap month keeps festivals in season

This is why Ramadan moves through the seasons over a 33-year cycle while Chinese New Year stays in late January or February.

A lunar age is consequently higher than a solar one: about 3% more years have passed by lunar count, so 30 solar years is roughly 31 lunar years.

The Traps in Date Arithmetic

Months are not 30 days. Adding one month to 31 January has no correct answer, and every library picks differently — 28 February, 2 March or an error. Decide which your business needs before the edge case decides for you.

Days are not always 86,400 seconds. Daylight saving makes one day 23 hours and another 25. Adding n * 86400000 milliseconds drifts by an hour twice a year, which is enough to move a date across midnight and return an answer one day out.

``javascript // Correct — the Date object normalises overflow and handles DST const addDays = (date, days) => { const result = new Date(date); result.setDate(result.getDate() + days); return result; };

// Correct — calendar days, unaffected by DST or time of day const daysBetween = (a, b) => { const utc = (d) => Date.UTC(d.getFullYear(), d.getMonth(), d.getDate()); return Math.round((utc(b) - utc(a)) / 86400000); };`

Months are zero-indexed in JavaScript. new Date(2026, 0, 1) is January. new Date(2026, 12, 1) is January 2027, silently.

Parsing is not portable. new Date("2026-08-30")is parsed as UTC, whilenew Date("2026/08/30")` is parsed as local — the same calendar date, a day apart in some zones. Always parse ISO 8601, and construct with explicit components when the time matters.

Time Zones Decide the Answer

Question	Depends on
How many days until an event?	The viewer's zone
Is this subscription expired?	UTC, always
What day of the week was this?	The zone the event happened in
When does "tomorrow" start?	The viewer's zone

Store timestamps in UTC and convert for display. Storing local times without an offset makes the data unrecoverable — you cannot tell later which zone it meant, and DST transitions make some local times ambiguous or non-existent.

Reference Points

Interval	Days
Week	7
Month (average Gregorian)	30.44
Quarter	91.31
Year	365.2425
Leap year	366

The Gregorian rule — leap year every 4 years, except centuries, except every 400th — keeps the calendar within one day of the solar year for about 3,000 years.

Lunar Age Calculator