Now im confused about the system grid :O

i recognized that a cube with the scale of xyz 1 1 1 , uses up 2 view-grid cells.
So the view-grid must be set to 0.5 units.
Now when i move the cube’s location to z 1, it moves only 0.5 !!

Is the cube now 1 1 1 unit or not ?

Or does even each object have its own relative system grid and i don’t know it ?

You’re confusing scale and dimension.

The default cube’s dimensions are 2 x 2 x 2 Blender Units:

This has nothing to with the scale, which is an indicator for a size transformation in Object mode.

aah i can see clearly now ! thx a lot.

just seeing that Dimensions and Scale are kinda interlocked in 1:2 ratio with each other.
when i change the dimension, scale is changed accordingly.
What is the good reason for that ?

Can i unlink Dimension and Scale from each other, or set the ratio to 1:1 ?

If you scale the cube and then press Alt-A > Rotation and Scale (in Object mode), you’ll reset the scale to 1,1,1 while retaining the new scale.

Apply object scale / rotation with Ctrl+A

If you scale and object in edit mode the scale of the object is unchanged

k i c, this way the relation between the object coordinates and scene coordinates are frozen.