20 miles in km Unit Conversion Calculator km to miles Mile Kilometer Meter Centimeter Millimeter Angstrom Fathom Yard Foot Inch Hand Finger Bamboo Barleycorn Kilometer Mile Meter Centimeter Millimeter Angstrom Fathom Yard Foot Inch Hand Finger Bamboo Barleycorn Kilometer, often abbreviated as 'km', is a unit of length in the metric system, primarily used to measure longer distances.