Completed age from birth
Enter a birth date and a reference date. The page shows the completed age, the years, months, and days that remain, the calendar days lived, and the next birthday. A February 29 birthday uses February 28 in a non-leap year. A local day of 23 or 25 hours does not change the count. The birth date is not saved, and the page does not decide a legal age.
Completed years, then the remainder
Completed age is the number of full years reached on the reference date. The longer line keeps those years and adds the months and days still left. The page does not count hours, and it does not decide whether someone meets a legal age. Two dates that are not a birth date and a reference date belong on the date calculator.
How the completed age is reached
The page compares the two calendar dates. Today sets the reference date to this device's local date. Reset clears the birth date, returns the reference date to today, and clears the result. If the birthday has not yet occurred in the reference year, the completed age is the year gap minus one. If the birthday is that day or has already passed, the completed age is the year gap. A future reference date is allowed. A reference date before the birth date is not.
Full years and the months and days after them
The completed age is the full years only. The longer result keeps those years and adds the months and days from the birth date to the reference date. On the birthday itself, the months and days are zero.
A February 29 birthday in a common year
A February 29 birthday stays on February 29 in a leap year. In a year that is not a leap year, that birthday is February 28. On 28 February of such a year, the birthday counts as reached. It does not move to March.
Days lived and the next birthday
Days lived are calendar days from the birth date to the reference date. The same date is 0 days, and the next date is 1 day. If the birthday is still ahead in the reference year, the next birthday is that year's date. If the reference date is the birthday, the page says so and the days remaining are 0. If that year's birthday has passed, the next birthday is the following year's date, using February 28 when that year has no February 29. To watch the time left until that birthday, set a countdown to that date.
Age on a date you choose
- The completed age today, using this device's date as the reference.
- The completed age on a school date or a work date that is not today.
- The calendar days lived, and the days left until the next birthday.
What this age leaves out
- The result is a completed age from calendar dates. Korean counting age is not calculated.
- The length of a local day is ignored, so daylight saving time does not change the age or the day count.
- Accepted years are 1 through 9999. A next birthday outside that range is rejected.
- Hours and minutes are not part of this calculator, and neither is a legal-age decision.
- The birth date and the reference date stay on the open page. They are not saved in this browser, and they are not sent to a server.
- Today on this device is offered as the reference date after the page opens. It is not written into the page file. The birth date stays empty until you enter it.
Questions about completed age
What does completed age mean on this page?
It is the number of full years reached on the reference date. If the birthday in that year has not happened yet, the year gap is reduced by one.
When does a February 29 birthday use February 28?
In a leap year the birthday stays on February 29. In any other year it is February 28, for the completed age, the next birthday, and the days remaining. It does not move to March.
What do the years, months, and days show?
They keep the full years, then the months and days from the birth date to the reference date. On the birthday itself, the months and days are zero.
How are the days lived counted?
They are calendar days from the birth date to the reference date. The birth date itself is 0 days. The next day is 1 day. A local day of 23 or 25 hours is still one calendar day.
When is the next birthday still this year?
When the birthday is still ahead of the reference date in that year. If the reference date is the birthday, the days remaining are 0. If the birthday has passed, the next one is the following year.
Does this page calculate Korean counting age?
No. It calculates completed age from calendar dates. It does not decide whether someone meets a legal age.
Can the reference date be a day other than today?
Yes. Change it and press Calculate. A future date is allowed. A date before the birth date shows a message instead of an age. Neither date is saved, and years run from 1 through 9999.