Units = Ohms per Square (Ω/sq) or (Ω/□)
The resistance of one square of material, with a uniform thickness, is the same, regardless of size.
R = Resistance
= Material Resistivity
W = Width
L = Length
T = Thickness
A = Cross sectional Area = W × T
Notice that if length and width are equal, then that term goes to 1 and only the resistivity and thickness matter.
Sheet resistance measurements must be made with connections across the entire side of the square