The thickness of the copper on a prototype board is called out under the filter titled material. A common example of one of the options is “Copper Clad FR4, Single Sided, 1 oz.” The meaning of 1oz in that material description calls out the thickness of the copper foil.
1oz means a weight of 1oz of copper is evenly tiled in 1 square feet (ft2) of the area to achieve the thickness.
That is, 1 oz = 28.35 g / ft2
Copper density = 8.93 g / cm3
1 square feet = 929.03 cm2
Therefore, 1oz copper foil thickness = 28.35 / 8.93 / 929.03 ≈ 35um or 1.35 mil
General PCB thicknesses includes these dimensions 1/2 oz = (17.5um) , 1oz = (35um) , 2oz = (70um) , and 3oz =(105um)
On our website we just list the board thickness which is the total thickness of both the copper foil and the FR4 which is the glass reinforced epoxy laminate.