In Object Mode, I can input the dimensions in the Properties Panel. But how do I scale to specific measure units in Edit Mode? I have tried to figure it out myself, honestly, but I just don't get it. I tried scaling with the shortcuts sx0.12 and sy0.07, but that seem to use percentage of the current size instead of centimeters.
Thanks, guess I have to use Translate, then ... and some wacky hacks:
Created a plane with 5 cm radius = 10 x 10 cm
Current width = 10cm
Target width = 12cm
Needed extra width = 12-10 = 2 cm
Select left edge of plane
Input this: gx0.02
Current height = 10cm
Target height = 12cm
Needed extra height = 7-10 = -3 cm
Select top edge of plane
Input this: gy-0.03
Found a better hack:
In the Properties panel, under Mesh Display, I set a checkmark at [v] Length
Then select one of the edges. Press G to move it, and X/Y/Z to lock it to that axis. Now I just keep an eye on the numbers, and drag it until it matches what I want (hold Shift for more precision)