Glyph sizing control techniques are described for digital content that provide insight regrading a true size of glyphs when rendered using a respective font and also leverages this insight to control font sizing and alignment. In one example, a glyph sizing system outputs a plurality of options to specify a unit-of-measure to control an actual size of a glyph as rendered in a user interface. Examples of units of measure include a capital height, x-height, ICF-height, dynamic height, object height, width, and other spans along a dimension, e.g., based on ascent, descent, or other. These units of measure are leveraged by the glyph sizing system to surface information regarding an actual size of respective glyphs for that unit-of-measure and control glyph sizing and arrangement.