With AutoCAD, the units used are down to you.

Click here if you use 1 unit to represent 1 m

Printing a DWG To PDF.pc3 without layout

Scale 1:1 set 1mm = 1 unit

Scale 1:50 set 1mm = 50 units

Scale 1:100 set 1mm = 100 units

Scale 1:200 set 1mm = 200 units

Scale 1:500 set 1mm = 500 units

Scale 1:1000 set 1mm = 1000 units

Click on one of the other options to activate the scale change before previewing.