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 2004? Age Calculator

Your date of birth

Date of birth

Calculate age as of

Also show Korean age

Results

Total days: 8,122
Total weeks: 1,160
Total months: 266
Total hours: 194,928
Seconds lived: 0

2004 age range (2026)

	Age
Age after birthday (earliest DOB in year)	22
Age before birthday (latest DOB in year)	21

Browse 2004 by month

january 2004 february 2004 march 2004 april 2004 may 2004 june 2004 july 2004 august 2004 september 2004 october 2004 november 2004 december 2004

Example dates in 2004

Birth date	Current age	Calculator
January 1, 2004	22	Open
June 15, 2004	22	Open
September 10, 2004	22	Open
December 31, 2004	21	Open

All dates in 2004 (sample)

Date	Page
January 1, 2004	january-1-2004
January 15, 2004	january-15-2004
January 31, 2004	january-31-2004
February 1, 2004	february-1-2004
February 15, 2004	february-15-2004
February 29, 2004	february-29-2004
March 1, 2004	march-1-2004
March 15, 2004	march-15-2004
March 31, 2004	march-31-2004
April 1, 2004	april-1-2004
April 15, 2004	april-15-2004
April 30, 2004	april-30-2004
May 1, 2004	may-1-2004
May 15, 2004	may-15-2004
May 31, 2004	may-31-2004
June 1, 2004	june-1-2004
June 15, 2004	june-15-2004
June 30, 2004	june-30-2004
July 1, 2004	july-1-2004
July 15, 2004	july-15-2004
July 31, 2004	july-31-2004
August 1, 2004	august-1-2004
August 15, 2004	august-15-2004
August 31, 2004	august-31-2004
September 1, 2004	september-1-2004
September 15, 2004	september-15-2004
September 30, 2004	september-30-2004
October 1, 2004	october-1-2004
October 15, 2004	october-15-2004
October 31, 2004	october-31-2004
November 1, 2004	november-1-2004
November 15, 2004	november-15-2004
November 30, 2004	november-30-2004
December 1, 2004	december-1-2004
December 15, 2004	december-15-2004
December 31, 2004	december-31-2004

Age milestones

Age	Year reached
1	2005
5	2009
10	2014
13	2017
16	2020
18	2022
21	2025
25	2029
30	2034
40	2044
50	2054

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

2002 2003 2004 2005 2006