Accurate printing output

Printing to scale produces dimensions which are slightly off when an Architects scale is used to determine real world dimensions. Exp. - a 20’-6" may measure 19’ 3" with the Architects scale.
This is true for printouts from both Sketch and Layout.
Printer is a Epson Workforce 7520, paper size 11" x 17" on a Mac.

Don’t know what you purpose is but; neither an Architects scale nor printer are perfect as well as the conversion from 32 / 64 float.
Suggest changing units to decimal at least 3 places then recheck measurements and use a secondary standard measure device to elimate possible error there.