Centum weight or Hundred weight / hundredweight's a unit of measurement for mass in U.S. customary units and in the Imperial system in the United Kingdom, Ireland, the Channel Islands and the British Commonwealth. Definition The definition of the hundredweight differs in the two major systems of English customary units: In Imperial units, a hundredweight ('long')'s defined as 112 pounds avoirdupois, or 8 stone, or four quarters (50.80234544 kg). This's so close to 50 kg that the transition to me… (More on Hundredweight)