Conventionally, when a calligrapher uses an edged-pen for writing, the nib size and number of nib widths determine the body height of the letters. The height is generally known as the x-height, because it is the height of the letter x. To measure the x-height the nib edge is kept vertical whilst accurately making horizontal steps starting at the write-line. Each script has a certain weight, i.e. 5 nib-widths for Italic minuscules. So the x-height for Italic Minuscules would be the distance from the write-line to the top of the 5th step.Designed for use with the William Mitchell Square-Cut Round Hand Pens the X-height Calculator makes the above measuring procedure unnecessary.The X-height Calculator replaces the need of making horizontal steps on the paper. Once you have chosen the nib size, simply pull the slider out until required number of nib widths (NW) appears in the NW window. Identify the chosen nib size and read off the x-height value.
Example: To find the x-height for 5 nib widths of a size 3 nib, pull the slider out until the number 5 appears in the NW window. Look down the list of nib sizes until you see the number 3. The corresponding value in the x-height window is 6.0Therefore 5nw of a No.3 nib is 6.0mmIf you prefer working in Inches then apply the same method, but use the other side of the X-Height Calculator. (5nw of a No.3 = ¼”)