How do I convert centimeters to millimeters?
Add a zero, or more properly multiply by 10. Ten millimetres to a centimetre, so 5 cm is 50 mm and 15 cm is 150 mm.
On a ruler it's just counting the small marks. It matters more in kitchens, where a cabinet sold as 60 cm wide is a 600 mm unit and a slipped zero is a tenfold mistake.
What is a centimeter?
A centimeter (cm) is one hundredth of a meter and just under four tenths of an inch (0.3937 inches). The prefix comes from the Latin centum, a hundred.
Divide centimeters by 30.48 to get feet, or multiply feet by 30.48 to get centimeters. The factor is exact, as a foot is 30.48cm, and a single centimeter is about 0.0328 feet.
The centimeter was the base unit of length in the CGS (centimeter, gram, second) system that physicists used before SI, which is why older physics talks about dynes and ergs.
What is a millimeter?
A millimeter is a thousandth of a meter (1/1000) which is the SI (International System of Units) unit of length. It is normally used to measure small lengths like the thickness of a sheet of paper or the dimensions of a small object.
One millimeter is approximately equal to 0.03937 inches (about 1/25th). Presicely there are 25.4 millimeters in an inch and it is often used in science and engineering. It is used in countries that have adopted the metric system.
You may come across millimeters when measuring the size of electronic components, jewelry or even the thickness of a fingernail.