Age Calculator

How to use this calculator for age

There are only three easy steps to figuring out how old you are right now. First, pick your birth date from the date picker or type it in the "Date of Birth" box. You can put the day, month, and year in any order you like.

Step 2: Next, keep the "Age as of" field set to today's date for your present age, or modify it to any date in the past or future. Do you want to know how old you'll be when you turn 50? Just type in that date instead.

Step 3: Click the "Calculate" button to get your findings right away. It shows your age in years, months, and days. Below that, you'll see how old you are in total months, weeks, days, hours, minutes, and even seconds.

What is age calculation and why is it important?

Age computation tells you exactly how long it has been since a person was born. This idea that seems basic has a lot of importance in everyday life, from figuring out who can go to school to who can retire to who can drink legally to who pays for insurance. Accurate age calculation is important for all government forms, medical records, and legal documents.

Most people can tell you how old they are in years. But exact age measurement goes much further, breaking it down into months, weeks, days, hours, minutes, and seconds. Healthcare providers who keep track of how babies are growing need to know how old they are in weeks. Immigration authorities check ages down to the exact day. Insurance actuaries figure out your premiums based on the exact age you were when you bought the insurance.

The Gregorian calendar is the global standard, and most countries use it for formal reasons. In this system, a person is born with an age of zero and gets one year older every year on their birthday. This may seem simple to people in the West, but many cultures have utilized various tactics in the past, and some of these approaches are still used in social settings today.

The math that goes into figuring out someone's exact age

To find out someone's exact age, you need to do more than just subtract. The method needs to take into account the fact that months can have different lengths, that there are leap years, and that your birth date is not the same as the present date.

Simple age formula

To find your age in whole years, subtract your birth year from the current year and then add the adjustment.

If your birthday has not happened yet this year, the adjustment is 1. If it has, the adjustment is 0.

Sample

• The year now (2025) minus the year of birth (1990) equals 35.
• Since March 10 comes before August 15, take away one.
• 34 years old

How to figure out months and days

If the current day is less than the birth day, subtract 1 from the months and add the total days from the previous month to the present day. Then, deduct the birth day.

Changing age into other units

List of conversions:

• Total days = (Years x 365) + (Leap years in range x 1) + (Months x average days) + Days
• Total hours = 24 times Total days
• Total minutes = Total hours times 60
• Total seconds equals Total minutes times 60

Conversions note: For accuracy, use 365.2425 days per year (the average for the Gregorian calendar) or count the actual days, including leap years.

How leap years change your age

Leap years make things more complicated, and many calculations don't take it into account. There is an extra day in the Gregorian calendar (February 29) that most people don't understand.

All the rules for leap years

• The year can be divided by 4 without a remainder, AND
• The year does NOT divide evenly by 100, UNLESS
• The year also divides equally by 400.

Examples

• 2024 is a leap year since it may be divided by 4.
• 2100 is not a leap year because it may be divided by 4 and 100 but not 400.
• Example 3: 2000 is a leap year since it may be divided by 4, 100, and 400.
• 1900-Divisible by 4 and 100, but not 400-Not a leap year

February 29: What about people born on this day?

There are about 4.1 million people in the globe who were born on February 29. They are dubbed "leaplings" or "leap day babies." This is because their real birthday only happens every four years, which makes for some fascinating legal and social circumstances.

Legal recognition is different in each area. In the UK, babies born on leap day officially turn one year older on March 1 in years that aren't leap years. February 28 is the official birthday of Taiwan and Hong Kong. Most states in the U.S. let people pick between February 28 and March 1.

Age computation stays the same: leaplings age one year every year, just like everyone else. The date of the celebration is the only thing that changes. Our calculator gets these birthdays right by adding years to the age depending on the laws of the calendar for each date range.

Age systems in different parts of the world

Different cultures have different ways of measuring age. For international communication, document processing, and being aware of other cultures, it's important to know about these distinctions.

Western (international) age system

• Age starts at 0 when you are born
• Goes up by 1 every birthday
• Used for all legal purposes in most nations

How East Asians count their age

In the past, Korea, China, Vietnam, and Japan all had distinct ways of counting age.

• Newborns are one year old when they are born (counting time in the womb)
• Everyone gets a year older on January 1, not on their birthday.
• Result: Koreans looked 1 to 2 years older than their age in other countries.

For sample, a baby born on December 31, 2023 would be 0 years old in the world, but 2 years old in Korea on January 1, 2024.

Important news: On June 28, 2023, South Korea formally switched to the international age system for all legal and administrative reasons. Age may still come up in social situations.

Chinese traditional age is like Korean age, however the year starts on the Chinese Lunar New Year instead of January 1. Age at birth is 1, and it goes up on Chinese New Year.

Japan stopped using the ancient kazoedoshi system in 1950 and now only utilizes international age (man nenrei).

Things to avoid when figuring out someone's age

Real-life uses for calculating age

Knowing your exact age is useful in many real-life situations. Here are the main reasons why people utilize age calculators.

How to figure out someone's age in Excel or Google Sheets

Spreadsheet formulas can figure out how old a list of dates is automatically. Here are the most important formulas for each platform.

The DATEDIF function in Excel

A formula that shows "X years, Y months, Z days"

Note: Put the date of birth in cell A1. For calculations in the past or future, replace TODAY() with a specific date.

The same thing as Google Sheets

The DATEDIF function works the same way in Google Sheets as it does in Excel. It is strong and works well in all browsers.