To easiest by to measure millimeters is with a metric ruler or meter stick. If you have a metric ruler, note that the numbered lines represent centimeters and the unmarked lines represent millimeters. One centimeter is equal to 10 millimeters.

mm is used to measure objects less than 1 cm. In other words, 1mm = 1/10th cm or 10mm = 1cm. Let us look at the mm to cm conversion table to understand it better.

Common items that can be used to show tumor size in mm include: a sharp pencil point (1 mm), a new crayon point (2 mm), a pencil-top eraser (5 mm), a pea (10 mm), a peanut (20 mm), and a lime (50 mm).

One millimetre is equal to 1000 micrometres or 1000000 nanometres. Since an inch is officially defined as exactly 25.4 millimetres, a millimetre is equal to exactly 5⁄127 (≈ 0.03937) of an inch.