How to Calculate Age in Excel

This tutorial takes about 2 minutes to complete.

Before you start

This tutorial shows how to calculate someone's age in years from a birthdate stored in Column A of an Excel spreadsheet. You'll use Excel's built-in DATEDIF function — it works on any version of Excel that supports date functions.

No installation is needed if you already have Excel (desktop or web). If you don't, the free Excel for the Web version works just as well for this tutorial.

Step 1: Format your dates

Before Excel can calculate anything with your dates, it needs to know they're actually dates — not plain text. If you typed them in manually, Excel often treats them as text by default.

Highlight Column A (click the A header at the top of the sheet), then right-click and choose Format Cells. In the dialog that opens, select the Date category on the left, then pick the date format that matches how your dates are currently written (e.g., 14/03/2025 or March 14, 2025). Click OK.

Once you click OK, Excel will re-interpret your column as real dates. You can verify this by checking that the dates shift right-aligned (text stays left-aligned in Excel).

Step 2: Enter the DATEDIF formula

Now let's calculate the age. Click on cell B1 and type a heading like Age so you know what each column shows. Then click on cell B2 — this is where the first calculation will go.

In B2, enter this formula exactly:

=DATEDIF(A2,TODAY(),"Y")

Here's what each part does:

• A2 — the birthdate you want to calculate from (the cell in Column A on the same row)
• TODAY() — Excel's built-in function that returns today's date, so your result stays current without manual updates
• "Y" — tells DATEDIF to return the result in full years

Press Enter. The cell will display a number — that's the age in completed years as of today.

Step 3: Fill down to all rows

Your formula only works for one row right now. To apply it to every record in your list, click on cell B2 (the one with the formula), then look at the bottom-right corner of the selected cell — you'll see a small black plus sign (called the fill handle).

Double-click that fill handle, and Excel will automatically copy the formula down to match the last row that has data in Column A. Every row now shows the calculated age.

That's it — your entire list now has ages calculated from birthdates, and they'll update automatically every day because TODAY() always returns the current date.