Age Calculator - Calculator Soup

The age calculator provides age results in different units of time. You can find age or any time duration in years, months and days, months and days, weeks and days, or only days.

If you wanted to know "How many weeks have I been alive?" or "How many days have I been alive?" this calculator shows the answer in total weeks and total days. We also calculate age results in total hours, total minutes, and total seconds.

The latest update to this age calculator includes the option to calculate date of birth using age on any date. It can also calculate date of death using age at death so you can calculate a person's lifespan. If you know age only in years, or years and months, the calculator finds the date range in which a person was born.

What is My Age?

This chronological age calculator can help you calculate your age. Input your date of birth and today's date to find your current age. You can also input a different end date to see what your age would be on that day. You can see how many days are left until your next birthday or event date at the bottom of all age calculations.

How Old is My Child?

Parents of newborn babies or infants often need to count weeks or months to tell someone how old their child is. This calculator automatically provides weeks and months of age for any age calculation.

To find how many weeks old your newborn is, input their date of birth and click the Calculate button. The "Find Age on" boxes automatically include today's date but you can also input a date in the future. The calculator displays your child's age in weeks, and also months if applicable.

Calculate Date of Birth

If you know someone's age and the date on which they were that age, this calculator can find their date of birth. This is helpful for genealogy research when records list a person's age on a census date, marriage record, or other historical document.

Select "Date of Birth" from the Calculate dropdown menu, enter the age in years, months, and/or days, then enter the reference date when the person was that age. Click Calculate to find the date of birth. If you know only the age in years (without months and days), the calculator provides a date range when the person was born.

Calculate Date of Death

This calculator can determine a date of death when you know someone's date of birth and their age at death. This is useful for genealogy research to calculate an ancestor's lifespan, or verifying information from documents that list age at death rather than the actual date.

Select "Date of Death" from the Calculate dropdown menu, enter the date of birth and age at death, then click Calculate. If you know only the age in years (without months and days), the calculator provides a date range during which death occurred.

How This Calculator Calculates Age

This age calculator uses programming language date and time functions to calculate age. The calculator sends user inputs through the date and time functions to calculate the difference between two dates. Alternatively if the user inputs age and a reference date, the functions calculate date of birth or date of death.

How to Calculate Age

There are two ways to calculate age or date difference by hand. In one, you can calculate age in total number of days as the sum of:

• Number of years, x, with 365 days = 365 * x plus,
• Number of leap years, y, with 366 days = 366 * y plus,
• Number of days in the remaining partial year

Your result will be a number of years, plus the number of days in the current partial year.

In the second method you can set up the dates like long subtraction. Put dates in the format yyyy mm dd with the current or more recent date on the top, and the older date on the bottom. Follow these steps and the example below to find the difference between two dates as a subtraction problem.

• Set up the dates like you would set up long subtraction, listing the dates in year, month and day format from left to right.
• Start all the way on the right and subtract days. If necessary, borrow 1 from months. The number of days borrowed will be equal to the number of days in the month you are shifting to.
• Then move to the left and subtract months. If necessary, borrow 1 year and add 12 months to months.
• Move to the left again and subtract years.
• The age or date difference result will be in years, months, and days

Example Age Calculation

You want to know the age of a person on March 10, 2026. They were born on November 15, 2006.

Set up the dates like you would set up long subtraction, listing the dates in year, month and day format from left to right.

2026 3 10 − 2006 11 15 =

• Subtract days, 15 from 10. This would result in a negative number so you need to borrow months.
• Borrow 1 from the months column. When you borrow a month you are shifting back 1 month, from March to February. The number of days you are getting for that month is the number of days in that month, 28 in this case. Going from 3 (March), to 2 (February), move those days to the day column, adding them to the original 10 days there.
• 10 + 28 = 38
• Then subtract days.
• 38 - 15 = 23

2026 2 38 − 2006 11 15 = 23 days

• Subtract months, 11 from 2
• Borrow from years. Since all years contain exactly 12 months, simply borrow 1 year from 2026 and add 12 months to the 2.
• Then subtract 11 from 14
• 2026 - 1 = 2025
• 2 + 12 = 14
• 14 - 11 = 3

2025 14 38 − 2006 11 15 = 3 months 23 days

• Finally, subtract years, 2006 from 2025
• 2025 - 2006 = 19

2025 14 38 − 2006 11 15 = 19 years 3 months 23 days

The calculated age, or date difference, is 19 years 3 months 23 days.

Date difference from November 15, 2006 to March 10, 2026

How Many Days Until...?

If you want to calculate by hand how many days until some date or event, you need to account for extra days in leap years. You also need to know the months with 31 days, those months with 30 days, and the one month with 28 days.

Number of Days per Month

• January - 31 days
• February - 28 days in a regular year
• February - 29 days in a leap year
• March - 31 days
• April - 30 days
• May - 31 days
• June - 30 days
• July - 31 days
• August - 31 days
• September - 30 days
• October - 31 days
• November - 30 days
• December - 31 days

You can count the days until a special day like a birthday, Thanksgiving, the Fourth of July, or the start of your vacation. Assuming the date is less than a year away, tally up the number of days per full month between now and your target date. Then add the partial months -- the number of days left in this month, and the number of days in the partial month before your target date.

You can use this Age Calculator to find the number of days until an event date. Insert today's date in the "Date of Birth" field, and your target date on "Find Age on" field. The calculator will compute the number of days till your date and display it in the exact number of days.

Date Inputs

The age calculator allows you to input single digit days. You do not have to pad them with a leading zero if the date is less than 10. You should input the 4-digit year.

This calculator assumes the start date is day 0 and begins counting after one full day. For example if you input the dates 03/15/2022 and 3/18/2022 into the calculator you will get a total age of 3 days. Day 1 is the 16th, day 2 is the 17th, and day 3 is the 18th. We do not count the 15th because it is day 0.

How to Calculate Age from Birthdate in Excel

You can use Excel to keep track of age or time since a date or event. To find the number of years since a date of birth or event, input the month, day and year in a cell in Excel in MM/DD/YYYY format. Use the formula =DATEDIF(A1, TODAY(), "Y") to get age in number of years. In the formula, A1 refers to the cell that contains your date of birth or event.

If you need the number of months and days since the date of birth, use this formula in another cell: =DATEDIF(A1, TODAY(), "YM"). This will give you the full months. Finally, in another cell, type =DATEDIF(A1,TODAY(),"MD") to find the remaining days since the date of birth or event.

You can use the "CONCAT" function to string your results together like this: =CONCAT(A2, " years, ", A3, " months, ", A4, " days "). Here, A2, A3 and A4 refer to your outputs years, months, and days respectively.