The pound (lb) is an imperial unit of mass equal to exactly 0.45359237 kilograms, serving as the primary weight unit in the United States and parts of the British Commonwealth. Body weight, gym equipment, and packaged goods in America are almost always labeled in pounds. One pound equals 16 ounces or roughly 0.4536 kilograms.

The stone (st) is a British imperial unit equal to 14 pounds or about 6.35 kilograms, traditionally used in the United Kingdom and Ireland for body weight. When someone in the UK says they weigh 11 stone, they mean 154 pounds, a convention that persists in everyday conversation and medical records. One stone equals exactly 6.35029 kilograms.