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 2013? Age Calculator

Your date of birth

Date of birth

Calculate age as of

Also show Korean age

Results

Total days: 4,835
Total weeks: 690
Total months: 158
Total hours: 116,040
Seconds lived: 0

2013 age range (2026)

	Age
Age after birthday (earliest DOB in year)	13
Age before birthday (latest DOB in year)	12

Browse 2013 by month

january 2013 february 2013 march 2013 april 2013 may 2013 june 2013 july 2013 august 2013 september 2013 october 2013 november 2013 december 2013

Example dates in 2013

Birth date	Current age	Calculator
January 1, 2013	13	Open
June 15, 2013	13	Open
September 10, 2013	13	Open
December 31, 2013	12	Open

All dates in 2013 (sample)

Date	Page
January 1, 2013	january-1-2013
January 15, 2013	january-15-2013
January 31, 2013	january-31-2013
February 1, 2013	february-1-2013
February 15, 2013	february-15-2013
February 28, 2013	february-28-2013
March 1, 2013	march-1-2013
March 15, 2013	march-15-2013
March 31, 2013	march-31-2013
April 1, 2013	april-1-2013
April 15, 2013	april-15-2013
April 30, 2013	april-30-2013
May 1, 2013	may-1-2013
May 15, 2013	may-15-2013
May 31, 2013	may-31-2013
June 1, 2013	june-1-2013
June 15, 2013	june-15-2013
June 30, 2013	june-30-2013
July 1, 2013	july-1-2013
July 15, 2013	july-15-2013
July 31, 2013	july-31-2013
August 1, 2013	august-1-2013
August 15, 2013	august-15-2013
August 31, 2013	august-31-2013
September 1, 2013	september-1-2013
September 15, 2013	september-15-2013
September 30, 2013	september-30-2013
October 1, 2013	october-1-2013
October 15, 2013	october-15-2013
October 31, 2013	october-31-2013
November 1, 2013	november-1-2013
November 15, 2013	november-15-2013
November 30, 2013	november-30-2013
December 1, 2013	december-1-2013
December 15, 2013	december-15-2013
December 31, 2013	december-31-2013

Age milestones

Age	Year reached
13	2026
16	2029
18	2031
21	2034
25	2038

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

2011 2012 2013 2014 2015