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 1940? Age Calculator

Your date of birth

Date of birth

Calculate age as of

Also show Korean age

Results

Total days: 31,498
Total weeks: 4,499
Total months: 1,034
Total hours: 755,952
Seconds lived: 0

1940 age range (2026)

	Age
Age after birthday (earliest DOB in year)	86
Age before birthday (latest DOB in year)	85

Browse 1940 by month

january 1940 february 1940 march 1940 april 1940 may 1940 june 1940 july 1940 august 1940 september 1940 october 1940 november 1940 december 1940

Example dates in 1940

Birth date	Current age	Calculator
January 1, 1940	86	Open
June 15, 1940	86	Open
September 10, 1940	86	Open
December 31, 1940	85	Open

All dates in 1940 (sample)

Date	Page
January 1, 1940	january-1-1940
January 15, 1940	january-15-1940
January 31, 1940	january-31-1940
February 1, 1940	february-1-1940
February 15, 1940	february-15-1940
February 29, 1940	february-29-1940
March 1, 1940	march-1-1940
March 15, 1940	march-15-1940
March 31, 1940	march-31-1940
April 1, 1940	april-1-1940
April 15, 1940	april-15-1940
April 30, 1940	april-30-1940
May 1, 1940	may-1-1940
May 15, 1940	may-15-1940
May 31, 1940	may-31-1940
June 1, 1940	june-1-1940
June 15, 1940	june-15-1940
June 30, 1940	june-30-1940
July 1, 1940	july-1-1940
July 15, 1940	july-15-1940
July 31, 1940	july-31-1940
August 1, 1940	august-1-1940
August 15, 1940	august-15-1940
August 31, 1940	august-31-1940
September 1, 1940	september-1-1940
September 15, 1940	september-15-1940
September 30, 1940	september-30-1940
October 1, 1940	october-1-1940
October 15, 1940	october-15-1940
October 31, 1940	october-31-1940
November 1, 1940	november-1-1940
November 15, 1940	november-15-1940
November 30, 1940	november-30-1940
December 1, 1940	december-1-1940
December 15, 1940	december-15-1940
December 31, 1940	december-31-1940

Age milestones

Age	Year reached
1	1941
5	1945
10	1950
13	1953
16	1956
18	1958
21	1961
25	1965
30	1970
40	1980
50	1990

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

1938 1939 1940 1941 1942