Age Calculator.

Guide

How to use the Age Calculator

Two dates in, a full breakdown out. It works for your own age, a child's age for a school form, or how old a relative was on a certain date.

1. Enter the birth date in the Date of birth field. Month, day and year all need to be there.
2. Leave the Age on this date field blank to get the current age; it uses today's date.
3. To find an age on some other date, past or future, enter it in Age on this date. This is how you check how old someone will be on the first day of school or when a policy term ends.
4. Read the headline: age in years, months and days. The years figure is the one that goes on forms.
5. Scroll down for the totals: Total months, Total weeks, Total days, Total hours and Total minutes.
6. Check the extras: Born on a (the day of the week), and Next birthday with its date and weekday, plus Days until it.

How the math works

Age is counted the way a calendar counts, not the way a stopwatch counts. The calculator first finds how many full years have passed, meaning how many birthdays have come and gone. Then it counts full calendar months since the last birthday, then the leftover days.

"Calendar months" matters. A month is February or July at its actual length, not a flat 30 days. If you were born on the 14th, each new month of age begins on the 14th. If you were born on the 31st and a month has no 31st, that month's anniversary falls on its last day, and the leftover days are counted from there.

Total days are the exact count between the two dates, leap days included. Weeks are total days divided by 7 and rounded down. Hours are days times 24, minutes are hours times 60.

Worked example

Someone born March 14, 1991, checked on October 27, 2026.

Step	Count	Result
Full years	Birthdays passed; the 35th was March 14, 2026	35 years
Full months	March 14 to October 14, 2026	7 months
Leftover days	October 14 to October 27, 2026	13 days
Total months	35 × 12 + 7	427 months
Total days	Exact count, including 9 leap days	13,011 days
Total weeks	13,011 ÷ 7, rounded down	1,858 weeks (and 5 days)
Hours and minutes	13,011 × 24; × 60	312,264 hours; 18,735,840 minutes

The headline reads 35 years, 7 months, 13 days. March 14, 1991 fell on a Thursday. The next birthday is Sunday, March 14, 2027, which is 138 days away.

Sanity check on the total days: 35 years at 365 days is 12,775; the 9 leap days between 1991 and 2026 bring that to 12,784; the 227 days from March 14 to October 27, 2026 bring it to 13,011. The calculator does that count exactly, so you do not have to.

Where age counting gets weird

Leap-day birthdays

If you were born February 29, you get a real birthday only every four years. In every other year the calculator treats March 1 as the day you turn a year older. Someone born February 29, 2000 shows as 26 years, 7 months, 28 days on October 27, 2026, with only six actual February 29 birthdays behind them. Some places treat February 28 as the birthday instead, so if it matters for a legal deadline, check the rule that applies to you.

Days borrowed from a short month

Because months have different lengths, the days figure depends on which months the count crosses. A person born January 31, 2026 is, on March 1, 2027, counted as 1 year, 1 month and 1 day: January 31 to February 28 is the full month, then March 1 is one day. Someone born March 31, 2026 and checked the same 394 days later, on April 29, 2027, is 1 year, 0 months and 29 days, because the count crosses a 31-day month instead. That is not a bug; it is what calendar counting means.

Different cultures count differently

This calculator uses the international convention: you are 0 at birth and turn 1 on your first birthday. In the traditional East Asian system, a newborn is 1 and everyone gets a year older together at the new year, so a person born in 1991 would be 36 in 2026 rather than 35. Some communities still use that count for ceremonies even where official records use the international one. If someone's stated age does not match the calculator, this is often why.

Why "months" and "30 days" don't match

People sometimes divide total days by 30 and get a different month count. In the example, 13,011 ÷ 30 is 433.7, nowhere near 427. Real months average about 30.44 days, and the calendar method counts actual month boundaries rather than fixed blocks. For an infant's age at the pediatrician, a lease term, or an age cutoff on a form, the calendar count is the one people expect.

Weeks are different: they are a fixed length, which is why pregnancy and newborn ages are tracked in weeks. Use the total weeks figure for those.

Related calculators

If you want the number of days between any two dates, or you want to add or subtract a span of time from a date, use the Date Calculator. It also counts business days, which this one does not. The hours and minutes shown here are simply the total days multiplied out, so for a stretch of time that is not someone's age, the Date Calculator is again the better tool.

What this calculator doesn't do

It counts whole days only, so it ignores the time of birth and time zones. Someone born late at night in one zone and checked early in the morning in another could be a day off from the figure here, which matters for almost nothing except trivia.

It uses the Gregorian calendar throughout and does not convert from lunar or other calendars. A date of birth recorded in another calendar needs to be converted first.

Frequently asked questions

Results are computed in your browser from the numbers you enter; nothing is sent to us. Double-check anything you rely on. See the terms of use.