How can you convert inches to kilometers?
Multiply inches by 0.0000254 to get kilometers. The factor is exact: an inch is 25.4mm and a kilometer is a million millimeters.
100 inches is 0.00254km and 50 inches is 0.00127km. That's a lot of zeros – it's easier to go via meters (100 inches is 2.54 meters) and divide by 1,000.
It's a rare conversion, as an inch suits a pencil or a person's height and a kilometer suits a road. It mostly turns up in homework.
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 kilometer?
A kilometer is 1,000 meters, or about 0.621 miles. 'Kilo' is the Greek-derived prefix for a thousand. It is the unit for road distances nearly everywhere except the US and UK, which still use miles.
A kilometer is about 3,281 feet or 39,370 inches. At a walking pace of 5km/h it takes about 12 minutes to cover.
Going from kilometers to meters just means moving the decimal point three places. A mile has to be broken into 1,760 yards or 5,280 feet first, and neither of those is a round number of anything.