Kilometers per hour (km/h) is the most common speed unit outside the United States, displayed on speedometers and road signs across Europe, Asia, and most of the world. Highway speed limits, weather reports for wind speeds, and vehicle performance figures in these regions all use km/h. One kilometer per hour equals approximately 0.2778 meters per second or about 0.6214 miles per hour.

Mach (Ma) is a dimensionless speed unit representing the ratio of an object's speed to the speed of sound in the surrounding medium. At sea level under standard conditions, Mach 1 equals approximately 343 meters per second or 1,235 kilometers per hour, though this varies with altitude and temperature. Supersonic aircraft travel above Mach 1, while hypersonic vehicles exceed Mach 5.