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 2017? Age Calculator

Your date of birth

Date of birth

Calculate age as of

Also show Korean age

Results

Total days: 3,374
Total weeks: 482
Total months: 110
Total hours: 80,976
Seconds lived: 0

2017 age range (2026)

	Age
Age after birthday (earliest DOB in year)	9
Age before birthday (latest DOB in year)	8

Browse 2017 by month

january 2017 february 2017 march 2017 april 2017 may 2017 june 2017 july 2017 august 2017 september 2017 october 2017 november 2017 december 2017

Example dates in 2017

Birth date	Current age	Calculator
January 1, 2017	9	Open
June 15, 2017	9	Open
September 10, 2017	9	Open
December 31, 2017	8	Open

All dates in 2017 (sample)

Date	Page
January 1, 2017	january-1-2017
January 15, 2017	january-15-2017
January 31, 2017	january-31-2017
February 1, 2017	february-1-2017
February 15, 2017	february-15-2017
February 28, 2017	february-28-2017
March 1, 2017	march-1-2017
March 15, 2017	march-15-2017
March 31, 2017	march-31-2017
April 1, 2017	april-1-2017
April 15, 2017	april-15-2017
April 30, 2017	april-30-2017
May 1, 2017	may-1-2017
May 15, 2017	may-15-2017
May 31, 2017	may-31-2017
June 1, 2017	june-1-2017
June 15, 2017	june-15-2017
June 30, 2017	june-30-2017
July 1, 2017	july-1-2017
July 15, 2017	july-15-2017
July 31, 2017	july-31-2017
August 1, 2017	august-1-2017
August 15, 2017	august-15-2017
August 31, 2017	august-31-2017
September 1, 2017	september-1-2017
September 15, 2017	september-15-2017
September 30, 2017	september-30-2017
October 1, 2017	october-1-2017
October 15, 2017	october-15-2017
October 31, 2017	october-31-2017
November 1, 2017	november-1-2017
November 15, 2017	november-15-2017
November 30, 2017	november-30-2017
December 1, 2017	december-1-2017
December 15, 2017	december-15-2017
December 31, 2017	december-31-2017

Age milestones

Age	Year reached
10	2027
13	2030
16	2033
18	2035
21	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

2015 2016 2017 2018 2019