See, this is where using all that white space in the body of the message
would have come in handy... then you could have explained **exactly** what
you want and we wouldn't have to guess.
What are you actually after... the number of characters in the cell (what
your other responses have told you how to do) or do you have a mixture of
numbers, letters and, perhaps, other characters and you want (as your
Subject says), the count of only the letters? If that is what you meant, try
this...
=SUMPRODUCT(--ISNUMBER(SEARCH(MID(A1,ROW(INDIRECT("A$1:A"&LEN(A1))),1),"abcdefghijklmnopqrstuvwxyz")))
Rick