Convert between millimeters, centimeters, meters, kilometers, inches, feet, yards and miles.
Metric units (mm, cm, m, km) scale by powers of ten, which is why converting among them is just moving a decimal point. Imperial/US units (inches, feet, yards, miles) come from historical body-based measurements, so their ratios aren't round numbers — 12 inches to a foot, 3 feet to a yard, 1,760 yards to a mile.