Reference Designer Calculators

OZ to mils(inch) Convession

The formula converts Copper Plating Weight in oz to thickness in inch. This is useful for PCB designer willing to know the thickness corresponding to a copper plating weight to inch or mils.

The copper in a PCB is rated in ounces, and represents the thickness of 1 ounce of copper rolled out to an area of 1 square foot. For example a PCB that uses 1 oz. copper has a thickness of 1.4mils.

The thickness of the PCB Trace alongwith the width of the trace, determine the maximum current carrying capacity of the traces. You can use the Current Carrying Capacity Calculator to calculate the required trace width or the trace thickness.
Following is the formula cpw ( in oz) to thickness ( in mils) conversion. ( If you want to quickly check Table - you can see it here.

Thickness(in oz) = thickness (in mils) /1.37

Following is the formula thickness ( in mils) to cpw( in oz) conversion.

t ( in mils) = t ( in oz) * 1.37

  (Thickness in mils) :
  (CPW in oz)

If you are interested in derivation, you can use the following facts to convert the Cu / ft2 to mils

1 oz = 28.35 g = 0.02835 kg

Area = 1 ft2 = (0.304 m)2 = 0.0924 m2

Density (Cu pure) rho = 8950 kg / m3

Update July 9, 2012 - Thanks Sebastian at Agilent for pointing out the error in the equation. This has been corrected. The calculator itself was correct and has not been changed.