How do you convert inches to decimeters?
Multiply by 0.254. An inch is exactly 2.54 cm, and a decimetre is 10 cm, so the factor is exact too.
A 30-inch waist works out at 7.62 dm, and a 12-inch ruler is 3.048 dm.
Decimetres rarely leave the classroom – most people go straight to centimetres by multiplying by 2.54 and skip the extra decimal place.
What is an inch?
An inch is a length unit normally used in the United States and, occasionally, in the United Kingdom. It is defined as a twelth (1/12th) of a foot. The inch is normally subdivided into fractions of an inch such as the ½, ¼ and ⅛.
An inch was originally the width of a man's thumb. It is still the everyday length unit in the United States, and TV and computer screens are sold by their size in inches worldwide.
Inches are used in combination with other units of imperial measurement such as feet and yards. For example, a standard door in the United States a football field is 100 yards long or 300 feet or 3,600 inches.
What is a decimeter?
A decimeter (dm) is one tenth of a meter, or 10 centimeters. The 'deci' is the SI prefix for 10^-1.
The decimeter is rarely used by itself, since people go from centimeters straight to meters. You mostly meet it as the cubic decimeter, which is exactly one liter.
A decimeter is about 3.937 inches, so just under four. Divide inches by 3.937 – or multiply by 0.254 – to go the other way.