How To Calculate Age Using Excel

Excel Age Calculator

Calculate age in years, months, and days, similar to Excel’s DATEDIF function. Enter the birth date and the “as of” date.

Excel Formula	Description	Example (Birth: 1990-08-15, As of: 2023-06-10)
DATEDIF(A1, B1, "y")	Complete years	32
DATEDIF(A1, B1, "m")	Complete months	393
DATEDIF(A1, B1, "d")	Total days	11986
DATEDIF(A1, B1, "ym")	Months after full years	9
DATEDIF(A1, B1, "md")	Days after full months	26
DATEDIF(A1, B1, "yd")	Days after full years	300

Table showing examples of Excel’s DATEDIF function with different units.

What is Calculating Age in Excel?

Calculating age in Excel involves determining the duration between a birth date and a specific end date (often the current date) in terms of years, months, and/or days. The most common and effective way to how to calculate age using Excel is by using the `DATEDIF` function. This function is specifically designed to calculate the difference between two dates in various units.

Anyone who needs to find the age of individuals or the duration between two dates can benefit from learning how to calculate age using Excel. This includes HR professionals (for employee records), teachers (for student ages), researchers, demographers, and even individuals managing personal data.

A common misconception is that simply subtracting the birth year from the current year will give the correct age. This is often inaccurate because it doesn’t account for the month and day of birth relative to the current month and day. The `DATEDIF` function correctly handles these nuances for precise age calculation.

Excel’s Age Calculation Formula (DATEDIF) and Mathematical Explanation

The core formula for how to calculate age using Excel is `DATEDIF(start_date, end_date, unit)`.

• `start_date`: The earlier date (e.g., birth date). This must be a valid Excel date.
• `end_date`: The later date (e.g., today’s date or another specific date). This also must be a valid Excel date.
• `unit`: A text string specifying the unit of time you want the difference to be returned in.

The `DATEDIF` function calculates the number of full days, months, or years between the two dates based on the unit specified.

Variables Table:

Variable	Meaning	Unit/Format	Typical Range/Value
start_date	The beginning date (e.g., birth date)	Excel Date Serial Number or Date String	e.g., “1990-08-15” or cell reference
end_date	The ending date (e.g., current date)	Excel Date Serial Number or Date String	e.g., “2023-06-10”, TODAY(), or cell reference
"y"	Unit for complete years	Text String	Returns number of full years
"m"	Unit for complete months	Text String	Returns number of full months
"d"	Unit for total days	Text String	Returns number of days
"ym"	Unit for months excluding full years	Text String	Returns months remaining after full years
"md"	Unit for days excluding full years and months	Text String	Returns days remaining after full years and months
"yd"	Unit for days excluding full years	Text String	Returns days between dates as if they were in the same year

When calculating “y”, “ym”, and “md”, Excel essentially subtracts the dates component by component, borrowing where necessary, much like manual date subtraction.

Practical Examples (Real-World Use Cases)

Example 1: Calculating Employee Ages

An HR department needs to calculate the current age of all employees based on their birth dates listed in column B, with today’s date being June 10, 2023.

• Birth Date (B2): 1985-03-20
• Today’s Date (C2 or using TODAY()): 2023-06-10
• Formula for Age in Years (D2): =DATEDIF(B2, TODAY(), "y") Result: 38
• Formula for Age in Years, Months, Days (E2): =DATEDIF(B2, TODAY(), "y") & " years, " & DATEDIF(B2, TODAY(), "ym") & " months, " & DATEDIF(B2, TODAY(), "md") & " days" Result: “38 years, 2 months, 21 days”

This allows the HR department to quickly see the precise age of each employee, useful for benefits administration or retirement planning.

Example 2: Determining Age at a Specific Event

A school wants to find the age of students on the first day of the school year, September 5, 2023.

• Birth Date (B2): 2012-11-15
• School Start Date (C2): 2023-09-05
• Formula for Age in Years (D2): =DATEDIF(B2, C2, "y") Result: 10
• Formula for Full Age (E2): =DATEDIF(B2, C2, "y") & " years, " & DATEDIF(B2, C2, "ym") & " months, " & DATEDIF(B2, C2, "md") & " days" Result: “10 years, 9 months, 21 days”

This shows how to calculate age using Excel for a specific point in time, not just the current date.

How to Use This Age Calculator

Our calculator mirrors the way you would how to calculate age using Excel‘s `DATEDIF` function:

1. Enter Birth Date: Input the year, month (1-12), and day (1-31) of birth into the respective fields.
2. Enter As of Date: Input the year, month, and day for the date at which you want to calculate the age. If left blank, it defaults to today’s date when you click “Calculate Age”.
3. Calculate: Click the “Calculate Age” button.
4. Read Results:
   • Primary Result: Shows the age in full years, remaining months, and remaining days.
   • Intermediate Results: Displays the age in total decimal years, total months, and total days.
   • Formula Explanation: Shows the equivalent Excel `DATEDIF` formulas.
5. Dynamic Chart: The bar chart visually represents the years, months, and days components of the calculated age.
6. Reset: Use the “Reset” button to clear inputs and results or return to default values.
7. Copy Results: Use the “Copy Results” button to copy the main age result and intermediate values to your clipboard.

This tool helps you quickly understand how to calculate age using Excel without opening the application, and see the results instantly.

Key Factors That Affect Age Calculation Results

1. Start Date (Birth Date): The accuracy of the birth date is crucial. An incorrect birth date will lead to an incorrect age.
2. End Date (As of Date): The age is calculated relative to this date. Changing it changes the age. Using TODAY() in Excel makes it dynamic.
3. The Unit (“y”, “m”, “d”, “ym”, “md”, “yd”): The unit specified in `DATEDIF` determines what is returned (full years, total months, days between months, etc.). Understanding these units is key to getting the desired output when learning how to calculate age using Excel.
4. Leap Years: The `DATEDIF` function correctly accounts for leap years when calculating the total number of days (“d”) and when figuring out day differences (“md”, “yd”).
5. Date Format: Ensure dates are entered in a format Excel recognizes (or as year, month, day in our calculator) to avoid errors. Excel stores dates as serial numbers.
6. Time Component: Excel dates can include time. `DATEDIF` generally ignores the time component, focusing on the date part. If time is critical, other calculations might be needed.

Frequently Asked Questions (FAQ)

1. What is the DATEDIF function in Excel?

The `DATEDIF` function calculates the difference between two dates in years, months, or days. It’s essential for how to calculate age using Excel accurately.

2. Why can’t I just subtract the birth year from the current year to get the age?

This method doesn’t account for the month and day. Someone born on December 31st is 0 years old for almost the entire first year, but year subtraction would say 1.

3. How do I get today’s date in Excel for age calculation?

Use the `TODAY()` function as the `end_date` in your `DATEDIF` formula: =DATEDIF(birth_date_cell, TODAY(), "y").

4. What do “ym”, “md”, and “yd” mean in DATEDIF?

“ym” gives the number of months after subtracting full years. “md” gives the number of days after subtracting full years and months. “yd” gives the number of days between the dates as if they were in the same year.

5. Does DATEDIF handle leap years?

Yes, `DATEDIF` correctly accounts for leap years when calculating the difference, especially with the “d” unit.

6. What if the end date is before the start date?

The `DATEDIF` function will return a #NUM! error if the `start_date` is later than the `end_date`. Our calculator will show an error message.

7. How can I display age as “X years, Y months, Z days” in Excel?

You combine `DATEDIF` with different units and text concatenation: =DATEDIF(A1,B1,"y") & " years, " & DATEDIF(A1,B1,"ym") & " months, " & DATEDIF(A1,B1,"md") & " days".

8. Is DATEDIF available in all versions of Excel?

Yes, but it’s somewhat “hidden” or undocumented in some versions, though it works reliably. It was originally from Lotus 1-2-3 for compatibility.