How do I calculate my age from my date of birth?

Subtract your birth year from the current year. If your birthday has not happened yet this year, subtract one more year from that total. Then count the months and days separately using the same subtract-and-borrow method. This tool does all of that automatically. You just get the finished answer.

Can I calculate my age on a specific date?

Yes. Instead of leaving the calculate-as-of field on today, pick any date, past or future, and the tool works out your age as of that day. Use this for school enrollment cutoffs, immigration age requirements, or figuring out how old you will be on a future date like a wedding or retirement.

How does this handle leap years?

Leap years are built into the calendar math, not added as an afterthought. If someone's birthday is February 29, this tool treats it as February 28 in non-leap years for counting elapsed years, the same convention most legal and administrative systems use, while still calculating the exact day count correctly underneath.

What is chronological age?

Chronological age is the time that has passed since birth, measured in the calendar: years, months, and days. It is different from biological age, which estimates how old a body seems rather than how long a person has actually been alive. When a form or a doctor asks for your age, chronological age is what they mean.

How is Korean age different from international age?

Korean age starts at one, not zero, on the day someone is born, and everyone's age increases together on New Year's Day instead of on individual birthdays. Depending on birth month, that can put Korean age one or two years ahead of the international age most of the world uses. Toggle Also show Korean age to see both numbers at once.

How do I calculate age difference between two people?

Switch to the Age Difference tab, enter both birth dates, and the calculator returns the gap as years, months, and days, plus a flat day count if you need one number instead of three. It works the same way whether the gap is a few months or several decades.

How accurate is this online tool?

It is accurate to the day, using real calendar date math rather than a simplified days-divided-by-365 estimate. Leap years, varying month lengths, and the borrow-a-month logic are all handled correctly. The one thing it cannot account for is a wrong birth date typed in.

How do I calculate age in Excel?

Put the birth date in a cell, then wrap it in Excel's DATEDIF function with "Y", "YM", and "MD" as the unit arguments to pull out years, months, and days separately. The full formula is in the Excel section above. It is the same calendar-based approach this tool uses, just typed out manually.

Yes. Everything runs in your browser using JavaScript. Your birth date never leaves your device. There are no servers processing your information and no account required. You can disconnect from the internet after loading the page and the calculator still works.

Can I use this for my pet?

Yes. Click the Pet Age tab, choose dog or cat, and enter how many years old your pet is. The tool converts to human-equivalent age using the standard veterinary formula, not the old seven dog years equals one human year shortcut.

How Old Is Someone Born in 1999? Age Calculator

Your date of birth

Date of birth

Calculate age as of

Also show Korean age

Results

Total days: 9,949
Total weeks: 1,421
Total months: 326
Total hours: 238,776
Seconds lived: 0

1999 age range (2026)

	Age
Age after birthday (earliest DOB in year)	27
Age before birthday (latest DOB in year)	26

Browse 1999 by month

january 1999 february 1999 march 1999 april 1999 may 1999 june 1999 july 1999 august 1999 september 1999 october 1999 november 1999 december 1999

Example dates in 1999

Birth date	Current age	Calculator
January 1, 1999	27	Open
June 15, 1999	27	Open
September 10, 1999	27	Open
December 31, 1999	26	Open

All dates in 1999 (sample)

Date	Page
January 1, 1999	january-1-1999
January 15, 1999	january-15-1999
January 31, 1999	january-31-1999
February 1, 1999	february-1-1999
February 15, 1999	february-15-1999
February 28, 1999	february-28-1999
March 1, 1999	march-1-1999
March 15, 1999	march-15-1999
March 31, 1999	march-31-1999
April 1, 1999	april-1-1999
April 15, 1999	april-15-1999
April 30, 1999	april-30-1999
May 1, 1999	may-1-1999
May 15, 1999	may-15-1999
May 31, 1999	may-31-1999
June 1, 1999	june-1-1999
June 15, 1999	june-15-1999
June 30, 1999	june-30-1999
July 1, 1999	july-1-1999
July 15, 1999	july-15-1999
July 31, 1999	july-31-1999
August 1, 1999	august-1-1999
August 15, 1999	august-15-1999
August 31, 1999	august-31-1999
September 1, 1999	september-1-1999
September 15, 1999	september-15-1999
September 30, 1999	september-30-1999
October 1, 1999	october-1-1999
October 15, 1999	october-15-1999
October 31, 1999	october-31-1999
November 1, 1999	november-1-1999
November 15, 1999	november-15-1999
November 30, 1999	november-30-1999
December 1, 1999	december-1-1999
December 15, 1999	december-15-1999
December 31, 1999	december-31-1999

Age milestones

Age	Year reached
1	2000
5	2004
10	2009
13	2012
16	2015
18	2017
21	2020
25	2024
30	2029
40	2039
50	2049

How this is calculated

Calendar age in years counts completed birthdays. A quick estimate is reference year minus birth year, then subtract 1 if the birthday has not yet occurred in the reference year.
Exact age = years + months + days between birth date and reference date, borrowing days from the previous month when needed.

Age = Reference date − Birth date

Weeks ≈ total days ÷ 7. Hours = total days × 24. Minutes = total hours × 60 (exact for whole-day spans).

Nearby birth years

1997 1998 1999 2000 2001