One nice thing, though, is the SH3D will do the conversion for you. Used a US drawing as inspiration for part of a plan. Simply changed my preferences, drew up the plan in US measures, changed preferences and there were all the cm measurements (which had to be tweaked to comply with local building standards, but still).

Curiously, while the feet unit is generally abandoned in Europe, boat lengths are still commonly specified in feet (but not draught/beam). And in terms of building, by the way, you may find that the rule of 2,54 cm = 1 inch does not always apply.

• Construction beams are still, in places, referred to in inches (thumbs). For instance, a builder might suggest using two-by-four beams (2"×4" / to-tom-fire). But if even if sometimes called two-by-fours, the beams will actually be cut to metric standards (here cut 50mm×100mm and adjusted to 48mm×96mm).
• To add to the confusion, if you like some SH3D users work with plans from archives to rebuild old houses, beware that the old foot/inch units have not always been the same and different standards were used in different places - as shown in a Wikipedia scan.

ok

By Franz Mozhnik, Scan von wBenutzer:Henryart, 2004 [Public domain], via Wikimedia Commons