KM, Km, or km may stand for:

Science, computing, mathematics, information technology

• Kilometre (km)
• Kernel methods, computer science algorithms
• Km, an electric Motor constant
• KM (Knowledge Machine) programming language
• Kelley-Morse set theory, a mathematics set theory
• K_M, the Michaelis constant in Michaelis–Menten kinetics
• Knowledge Management comprises a range of practices used by organisations to identify, create, represent, and distribute knowledge for reuse, awareness and learning
• Series of Russian Steel Towers, e.g. 3803 KM, 30107 KM [1]

Places

• Kamenz (district), Germany (license plate indication)
• Messenia, Greece (license plate indication)
• KM Junction, West Virginia
• .km, Internet top-level domain (ccTLD) for Comoros (ISO 3166-1 alpha-2 country code)
• Kysucké Nové Mesto, town in Slovakia (its district code is KM)
• Kent-Meridian High School in Kent, Washington (abbreviated KM)
• Kosovska Mitrovica in Serbia

.km is the Internet country code top-level domain (ccTLD) for Comoros.

The kilometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: km; or ) or kilometer (American spelling) is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for ). It is now the measurement unit used officially for expressing distances between geographical places on land in most of the world; notable exceptions are the United States and the road network of the United Kingdom where the statute mile is the official unit used.