How to calculate ages before 1/1/1900 in Excel

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SUMMARY

Although Microsoft Excel date formulas can only use dates entered between 1/1/1900 and 12/31/9999, you can use a custom Microsoft Visual Basic for Applications function to calculate the age (in years) of someone or something that was first created before January 1, 1900.

Use Macro to Calculate Age

Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.
Excel enters dates prior to 1/1/1900 as text. This function works for dates entered as text beginning with 1/1/0001, normal dates, and can handle dates when the starting date is before 1900 and ending date is after 1900. To use the macro, follow these steps:
1. Start Excel. View the worksheet on which you want to use the function.
2. Press ALT+F11 to switch to the Visual Basic Editor.
3. On the Insert menu, click Module.
4. Type the following code in the module:
```' This is the initial function. It takes in a start date and an end date. Public Function AgeFunc(stdate As Variant, endate As Variant) ' Dim our variables. Dim stvar As String Dim stmon As String Dim stday As String Dim styr As String Dim endvar As String Dim endmon As String Dim endday As String Dim endyr As String Dim stmonf As Integer Dim stdayf As Integer Dim styrf As Integer Dim endmonf As Integer Dim enddayf As Integer Dim endyrf As Integer Dim years As Integer ' This variable will be used to modify string length. Dim fx As Integer fx = 0 ' Calls custom function sfunc which runs the Search worksheet function ' and returns the results. ' Searches for the first "/" sign in the start date. stvar = sfunc("/", stdate) ' Parse the month and day from the start date. stmon = Left(stdate, sfunc("/", stdate) - 1) stday = Mid(stdate, stvar + 1, sfunc("/", stdate, sfunc("/", stdate) + 1) - stvar - 1) ' Check the length of the day and month strings and modify the string ' length variable. If Len(stday) = 1 Then fx = fx + 1 If Len(stmon) = 2 Then fx = fx + 1 ' Parse the year, using information from the string length variable. styr = Right(stdate, Len(stdate) - (sfunc("/", stdate) + 1) - stvar + fx) ' Change the text values we obtained to integers for calculation ' purposes. stmonf = CInt(stmon) stdayf = CInt(stday) styrf = CInt(styr) ' Check for valid date entries. If stmonf < 1 Or stmonf > 12 Or stdayf < 1 Or stdayf > 31 Or styrf < 1 Then AgeFunc = "Invalid Date" Exit Function End If ' Reset the string length variable. fx = 0 ' Parse the first "/" sign from the end date. endvar = sfunc("/", endate) ' Parse the month and day from the end date. endmon = Left(endate, sfunc("/", endate) - 1) endday = Mid(endate, endvar + 1, sfunc("/", endate, sfunc("/", endate) + 1) - endvar - 1) ' Check the length of the day and month strings and modify the string ' length variable. If Len(endday) = 1 Then fx = fx + 1 If Len(endmon) = 2 Then fx = fx + 1 ' Parse the year, using information from the string length variable. endyr = Right(endate, Len(endate) - (sfunc("/", endate) + 1) - endvar + fx) ' Change the text values we obtained to integers for calculation ' purposes. endmonf = CInt(endmon) enddayf = CInt(endday) endyrf = CInt(endyr) ' Check for valid date entries. If endmonf < 1 Or endmonf > 12 Or enddayf < 1 Or enddayf > 31 Or endyrf < 1 Then AgeFunc = "Invalid Date" Exit Function End If ' Determine the initial number of years by subtracting the first and ' second year. years = endyrf - styrf ' Look at the month and day values to make sure a full year has passed. If stmonf > endmonf Then years = years - 1 End If If stmonf = endmonf And stdayf > enddayf Then years = years - 1 End If ' Make sure that we are not returning a negative number and, if not, ' return the years. If years < 0 Then AgeFunc = "Invalid Date" Else AgeFunc = years End If End Function ' This is a second function that the first will call. ' It runs the Search worksheet function with arguments passed from AgeFunc. ' It is used so that the code is easier to read. Public Function sfunc(x As Variant, y As Variant, Optional z As Variant) sfunc = Application.WorksheetFunction.Search(x, y, z) End Function ```
5. Save the file.
6. Type the following data:
```A1   01/01/1887
A2   02/02/1945
```
In cell A3, enter the following formula
=AgeFunc(startdate,enddate)
where startdate is a cell reference to your first date (A1) and enddate is a cell reference to your second date (A2).

The result should be 58.
NOTE: Check all dates before 1/1/1900 for validity. Dates entered as text are not checked by Excel.

REFERENCES

212536 How to Run Sample Code from Knowledge Base Articles

Properties

Article ID: 245104 - Last Review: January 25, 2007 - Revision: 5.1
APPLIES TO
• Microsoft Office Excel 2007
• Microsoft Office Excel 2003
• Microsoft Excel 2002 Standard Edition
• Microsoft Excel 2000 Standard Edition
Keywords:
kbhowtomaster KB245104