Global/Local Edgelengh and Gravity

Does anyone know how to make blender display the edges global lengh instead of the local lengh? So that I can recreate realworld Physics and find out if my Cube is 2cm oder 2m.
I was assuming that the 9.81 Gravity in the World buttons meant 9.81 blender Units per squaresecound, but if I look at the edge lengh of my cube, they both show 2.000 even though one is 10 times the size of the other one, so there has to be a global unit…

Can’t anyone help me please?
I need to recreate real life physics, but I don’t know how to set the right size/Gravity

In object mode select your cube and press ctrl-a and apply size and rotation. This applies any object mode scaling you have done and the edge lengths will be correct.