Convert from libra [Portugal, Spain] to zentner [Germany]

Unit Definition (libra [Portugal, Spain])
The libra [Portugal, Spain] a traditional unit of weight. The libra was the Roman unit from which the English pound is descended; the symbol "lb" for the pound comes from this unit. The Spanish and Portuguese units are larger, generally in the range from 1.011 to 1.016 English pound (very close to 460 grams). The Spanish libra equals 16 onzas, and the Portuguese libra equals 16 onças. The word "libra" is sometimes used now for the kilogram, a much larger unit.

Unit Definition (zentner [Germany])
The zentner is a traditional German unit of weight or mass, comparable to the traditional quintal and to the English hundredweight. Similar units were used in Scandinavia. Originally the zentner was equal to 100 pfund, or German pounds. 100 pfund varied from 110 to as much as 120 pounds avoirdupois (49.9-54.4 kilograms), depending on the market. After the introduction of the metric system in Germany, the zentner was redefined to equal to exactly 50 kilograms, which is about 110.231 pounds. In English, the zentner is commonly spelled centner.