libbra

Libbra (plural libbre) is a traditional unit of mass used in Italian and in many European languages. The term derives from Latin libra, meaning scales or balance, and gave rise to the English word pound. In ancient Rome, the libra was the basic unit of mass, divided into 12 unciae (uncia). Its weight varied by region and period, with a commonly cited value around 327.45 grams.

In modern practice, libbra usually refers to the avoirdupois pound, the customary mass unit used in the United States and historically in Britain. One libbra equals exactly 0.45359237 kilograms. Accordingly, 1 kilogram is approximately 2.20462262 libbre, and 1 libbra contains 16 oncie (ounces). There is also a smaller unit, the troy pound, used for precious metals, which weighs 373.2417 grams; in some historical contexts this is referred to as a “libbra troy.” The symbol for the pound is lb, derived from libra.

In contemporary usage in Italy and most of continental Europe, the libbra is largely superseded by the kilogram, but the term remains in older texts, in culinary contexts, and in some international trade or law where traditional measures persist. The Italian word libbra is sometimes abbreviated as lb in technical contexts, though metric notation in modern schools and science is typically kg.

See also: Pound, Kilogram, Avoirdupois system, Troy weight, Libra romana.