Pound (lbs)
The pound is the primary unit of mass in the United States and remains widely used in the United Kingdom. Abbreviated as "lb" from the Latin libra, it equals exactly 453.59237 grams. Whether you're stepping on a bathroom scale, buying groceries at a deli counter, or checking airline baggage limits, chances are the measurement is in pounds.
Definition
The international avoirdupois pound is defined as exactly 0.45359237 kilograms. It is subdivided into 16 ounces or 7,000 grains. The pound should not be confused with the troy pound (used for precious metals), which equals approximately 373.24 grams. In scientific contexts the kilogram is preferred, but the pound remains the legal unit of trade in the United States.
History
The pound traces its roots to ancient Rome, where the libra pondo ("a pound by weight") served as a standard trade weight of roughly 328 grams. As the Roman Empire spread, so did variations of the pound. Medieval England adopted its own version, and by the 14th century the avoirdupois pound of 7,000 grains had become the commercial standard. In 1959, six English-speaking nations signed the International Yard and Pound Agreement, fixing the pound at exactly 0.45359237 kilograms - the definition still in use today.
Common Uses
Pounds dominate everyday measurement in the United States. Body weight is almost always discussed in pounds, newborns are announced in pounds and ounces, and grocery stores price meat, cheese, and produce per pound. Gym-goers load barbells in pound increments, and shipping carriers quote weight limits in pounds. In the UK, pounds are used alongside kilograms - people commonly state their weight in stone and pounds but buy food in metric units.
Did You Know? Facts About Pound
- The abbreviation "lb" comes from the Latin libra, not from the English word "pound."
- A US dollar bill weighs almost exactly one gram, so 454 bills weigh about one pound.
- The heaviest pumpkin ever grown weighed 2,749 pounds (1,247 kg), set in Italy in 2021.
- Astronauts on the Moon weigh about one-sixth of their Earth weight in pounds because of lower gravity.
- The British slang "quid" for one pound sterling has nothing to do with the unit of mass - it likely comes from the Latin quid pro quo.