A millimeter is a unit of length measurement in the Standard International (SI) or "metric" system. A millimeter is the smallest unit of measurement of length on a standard ruler in the metric system. It is abbreviated mm. There are 10 mm in 1 centimeter.

One US teaspoon is 4.92 ml, and one US tablespoon is 14.78 ml. How many drops in a milliliter? There are approximately 20 drops of water in a milliliter.

Tumor sizes are often measured in millimeters (mm) or centimeters. 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).

A millimetre is about the width of a sewing needle. You would probably measure small items such as screws or lines on a plan using mm. There are 10 mm in a centimetre (cm). So if an object measures 12 mm then you could also write this measurement as 1 cm 2 mm.