The Character Cell Width and Height properties show the dimensions of the default font in real units. If you are designing in real units and plan to use the default font in your form, you will want to keep these dimensions in mind as you create items and boilerplate graphics that display text.
When you work in real units, it is up to you to ensure that the width and height of the text item's bounding box are compatible with the size of the font applied to the text item. Note also that on some platforms, the presence of an object border can reduce the amount of space available for displaying text. For example, setting the Bevel property of a text item can reduce the number of characters the item can display.
About converting coordinate system units
Specifying the coordinate system