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Unit system metric
Unit of length
Symbol dam 
Unit conversions
1 dam in ...... is equal to ...
   SI units    10 m
   imperial/US units    10.936 yd
 393.70 in

A decametre or dekametre[citation needed] (American spelling: decameter or dekameter[1]; symbol dam[1], sometimes unofficially Dm or dkm) is a very rarely used unit of length in the metric system, equal to ten metres.

This measure is included in the SI mostly for completeness: in principle, any combination of prefix and unit can be written, but many are rarely used in practice. One practical use of the decameter is for altitude of geopotential heights in meteorology. Meteorologists also use another seldom encountered SI prefix: hecto- in hectopascal (hPa). The volumetric form (see below) cubic decametre is convenient for describing large volumes of water such as in rivers and lakes.

The square decametre (dam2) also known as the are (a), is the basis for the hectare (100 dam2), the standard metric unit of land registry.

See also[edit]


  1. ^ a b Metric Prefixes, in How Many? A Dictionary of Units of Measurement, Russ Rowlett and the University of North Carolina at Chapel Hill.