About character units

In Windows client Design Mode, nearly all size and location measurements are calculated in terms of what we call Mongoose "character units." This can be confusing to developers used to calculating sizes and locations of objects in terms of pixels, ems, or other, more absolute, units of measure.

Mongoose character units are calculated in terms relative to the size of the base font designated for the Mongoose-based application, similar to percent measurement designations. These facts - that character units are relative measurements, and that their reference point is the base font size - are the two most helpful things to keep in mind when trying to size or position components or other aspects of Mongoose forms.

How are character units calculated?

To calculate the size of the character unit, we:

  • Measure the combined width of eight different alpha characters (ABCMabcm), using the default font and font size that is applied to the form. We calculate the average width of these eight characters as one character unit.
  • Multiply the height of the characters by 1.2. This allows for characters that extend below the baseline.