Here's a User-Defined function which will do the job:

Function test_string(first As String, second As String) As Integer
Dim first_len As Integer
Dim second_len As Integer
Dim i As Integer
test_string = 0
first_len = Len(first)
second_len = Len(second)
If (first_len = 0 Or second_len = 0) Then test_string = -1: Exit
Function
For i = 1 To Application.WorksheetFunction.Min(first_len, second_len)
If Mid(first, i, 1) = Mid(second, i, 1) Then
test_string = i
Else
Exit Function
End If
Next i
End Function

Just copy/paste it into a normal module.

Use it like the following:

=test_string(A1,B1)

where you have strings to be tested in A1 and B1. It will return the
number of consecutive matching characters as an integer, or -1 if one
of the cells is empty.

Hope this helps.

Pete

andy62 wrote:
I am wondering if there is any trick for identifying how much of a match two
text strings are? In my case, the two strings would start the same, but then
differ somewhere in the middle or the end. If I could identify the character
position where the difference occurs that would help me - and then maybe
divide that number by the length in characters of the first string to get a
percentage.

TIA