Calculate Age using Date of Birth

Let’s say you are preparing data where the user’s age is one of the important things to capture. The thing is, if you ask every user to enter his/her age, chances are they can give you an approx number.

But here’s the kicker: If you ask them their date of birth then you can easily calculate their accurate age from it.

In Excel, you can calculate a person’s age using different methods, but if you ask me, I have found that the best way is to use DATEDIF.

In today’s post, I’d like to share with you a simple way to calculate age in Excel using the date of birth with DATEDIF.

Quick Intro: DATEDIF

Before you calculate age you need to get a bit deeper into DATEDIF. DATEDIF is a mysterious function that is not listed in Excel’s functions list. But you can enter it and use it once you know what’s its syntax.

This function’s basic work is to calculate the difference between two dates returns the result in different ways. i.e. years, months, days or in years and months, month and days, years and days.

And this is the feature that makes it perfect to use in age calculation.



  • Date1 – The date from where you want to start the calculation of your interval.
  • Date2 – The date to which you want to calculate the interval.
  • Interval – It represents the unit of the time, which will return from the function.

Steps to Calculate Age in Excel using DATEDIF

Here you need to calculate age in a format in which you could show years, months, and days separately. For example, 26 Years, 8 months & 17 days. And for this, we need to combine DATEDIF three times.

calculate age in excel using datedif function and date of birth

Here are the steps.

1. Calculate the Completed Years of a Person’s Age

First of all, you need to calculate to total completed years between a date of birth and today’s date. And, for this the formula will be:


This will return completed years between two dates.

2. Calculate Completed Months of a Person’s Age after Completed Years

Next thing is to calculate the completed months. It means if your age is 26 Years, 5 months, and 19 days, we need to get 5 months in return.

The below formula can be used:


This will return the completed months between the date of birth and today’s date after the completed years.

3. Completed Days of a Person’s Age after Complete Years and Months

In the end, you need to calculate the days that are left after completing years and months. Here is the formula:


This will return the rest of the days between the date of birth and today’s date after completing years and months.

4. Combine All Three Formulas to Get the Actual Age

Now it’s time to combine all these to create an accurate age. Enter the formula below in a cell in your worksheet and replace Date-of-Birth with your actual birth date.

=”You age is “& DATEDIF(Date-of-Birth,TODAY(),”y”) &” Year(s), “& DATEDIF(Date-of-Birth,TODAY(),”ym”)& ” Month(s) & “& DATEDIF(Date-of-Birth,TODAY(),”md”)& ” Day(s).”

calculate age in excel using datedif function using date of birth combined formula

That’s all.