What is a Pound?

The pound equals exactly 0.45359237 kilograms under the 1959 international yard and pound agreement. The unit's name comes from the Latin 'libra pondo' (a pound by weight), and the abbreviation 'lb' derives from 'libra.' The pound has been the everyday weight unit in English-speaking countries for over a thousand years, with regional variations until 20th-century standardization. Today it remains the primary weight unit in the United States for body weight (a person is '170 lb' rather than 77 kg), groceries, and shipping; in the United Kingdom it persists alongside kilograms, especially for personal weight ('11 stone 4' = 158 lb). The pound relates to the ounce (16 oz = 1 lb), the stone (14 lb = 1 stone), the kilogram (1 lb ≈ 0.454 kg), and the US ton (2,000 lb = 1 ton). The international 'avoirdupois' pound is the common standard, distinct from the troy pound used for precious metals.

Visual reference for how the pound relates to other weight units. Each row links to the full converter for that pair.

• Human body weight in the US and UK
• Grocery and retail food pricing in the US
• Boxing and wrestling weight divisions

• ✓1 lb ≈ 453.6 g ≈ ½ kg. For mental conversion: kg = lb / 2.2.
• ✓1 lb = 16 oz exactly. American recipes often mix pounds and ounces.
• ✓UK shop labels often show kg and lb together; US labels are pounds only.

• ✗Using 2 instead of 2.205 when converting lb to kg — a 10% error on airline luggage.
• ✗Confusing mass pounds (lb) with pound-force (lbf) in engineering.
• ✗Assuming a British and American pound are different — they are identical (0.45359237 kg).