Modify this like so to meet your alphabetic characters only criteria.
In cell C1, use this formula (array entered via Ctrl+Shift+Enter):

=LEN(A1)-SUM(--((CODE(MID(A1,ROW(INDIRECT("1:"&LEN(A1))),
1))=CODE("A"))*(CODE(MID(A1,ROW(INDIRECT("1:"&LEN (A1))),
1))<=CODE("Z"))+(CODE(MID(A1,ROW(INDIRECT("1:"&LEN (A1))),
1))=CODE("a"))*(CODE(MID(A1,ROW(INDIRECT("1:"&LEN (A1))),
1))<=CODE("z"))))

This formula will return number of characters in the string that are
not alphabetic. Modify the validation rule in A1 to read as follows:

=B1*(C1=0)

Now user will receive the error message under two conditions:
1. More than 15 characters entered
2. Any character in string that is not A-Z or a-z

You will want to hide these columns, particularly the one that checks
non-alpha characters, because it returns an error if the input cell is
empty (#REF).

On Dec 19, 9:25 am, iliace wrote:
Here's an example of how this is possible. In B1, I have this
formula:

=LEN(A1)<=15

In A1, I have this custom validation rule:

=B1

If the input is more than 15 characters, user will get an error
message.

However, you must have calculations on automatic for this to function.

On Dec 19, 3:47 am, Anders wrote:

Hi,

How can i get excel to show requirement for validation?

For example I want people to type in a text max 15 characters, but I want
them to be able to see how many characters they can type. For example the
cell can show XXXXXXXXXXXXXXX and as they start filling it in they swap the X
for their own words.

I know I can do validation max 15 character length but then they get a error
box and need to keep taking away characters untill they get below 15. Its
better if they can see it straight away, how many to fill inn.

--
Regards Anders