Nope, it isn’t. The pipes of my AC are sold as 15cm, my monitor box said 68.5cm, my deodorant got 250ml in it and my E-Scooter tires show 2.5 bar on the pump’s display.

For monitors US companies unfortunately managed to screw up the default sizes for everyone so now laptops got “15.6 inches”, but both laptop and monitor packaging also usually says sth. like 40cm on it so that’s fine I guess.