Help selecting a scale to use:
Floor plans are usually drawn in 1/4" = 1'-0"
Larger plans a scale of 1/8" = 1'-0" may be used.
A small plan or a single room drawing, select a scale of 3/8" = 1'-0", 1/2" = 1'-0", 3/4" = 1'-0", or 1" = 1'-0" may be used to fit the size of your drawing format.
There are several flat rulers progressively numbered graduations 1/4, 1/8, 1/16, and 1/32nd for reading certain architectural drawings.