Ducky. We should have converted to metric years ago here in the USA. In the 1940’s and 1950’s North American mills started planing rough sawn boards that were full size 2”x 4” down to 1-12” x 3-1/2” but still called them 2 x 4’s.
I lived in many houses in Pa. And NY that had the full size studs which were rough on builders hands.