Answer 7—American-style PCB copper weight is specified in terms of ounces per square foot. In order to translate this into actual thickness, you need to know the density of copper, which is 8.96 g/cm³ at 20°C, plus a few English-to-metric conversions. 

Even if you are ordering your PCBs by the ounce, it’s still useful to know the actual thickness so you can calculate current density in high-power circuits.

Contributor: David Tweed