When choosing lettering sizes for monogram fonts there are more specific guidelines. Many embroiderers who work with single lettered monograms usually use letters that are 1 or 4 inches. Stackable monograms are often measured at 3.5 or 4 inches. Spelling out names generally fall at 1, 1.5 and 2 inches. Of course these are only guidelines; the main thing to keep in mind for monogramming is that it needs to fit within the hoop.
Take a look at some of the specific sizes recommended for monogramming fonts…