The measurement unit in the technical world are millimetres. Its abbreviation is mm.
All your plans have to be generated at this scale. Once the plan is supported by the Contour Engine, a black box appears on your previewed file. This box contains the external dimensions of your part. Do not forget to check the consistency.
Remember, 10 millimetres equals 1 centimetre (1cm = 10mm), and 1000 millimetres equals 1 meter (1m = 1000mm).