It was just pointed out to me by one of my colleagues that my post above might not be what you are looking for. Were you asking about the Help/Notes object, or about the note/notes fields available in the Customer/Contact. If you are looking for the limit for the Note or Notes fields for the Customer/Contact table, then the best way to find this is to go to Customize->Fields/Tables, and "Edit" either table to find these fields. To the right of the field on the next pop-up screen, you can see the maximum size the notes can be. For the Contacts table, it is 4000 limit, and for the Customer table the limit is 4095.