Calculate age in Microsoft Word

Assuming that you are using FormFields in a document that is protected for forms and that the bookmark name DOB is assigned to the formfield into which the date of birth is to be inserted and the bookmark name of Age is assigned to the formfield in which the age is to be displayed, running a macro containing the following code on exit from the DOB formfield will populate the Age formfield with the age in years.

Public Sub CalcAge()
Dim objAge As Word.FormField
Dim objBirthDate As Word.FormField
Dim datToday As Date
Dim intAge As Integer
Dim intYears As Integer

datToday = Date
Set objAge = ActiveDocument.FormFields("Age")
Set objBirthDate = ActiveDocument.FormFields("DOB")

    If IsDate(objBirthDate.Result) = False Then
      objAge.Result = ""
      Set objAge = Nothing
      Set objBirthDate = Nothing
    Else
        intYears = DateDiff("yyyy", objBirthDate.Result, datToday)
        If intYears > 0 Then
            intAge = intYears - Abs(DateDiff("d", datToday, DateAdd("yyyy", intYears, objBirthDate.Result)) > 0)
        End If
        objAge.Result = intAge
    End If

End Sub

Select all Open in new window

Hope this helps
I tweaked the code from Calculating age from a DOB field