When you need this conversion
US weights for international forms, gym plates marked in pounds, recipes and food packaging, and shipping quotes. Medical and scientific settings always use kilograms.
Quick reference
- 1 lb = 0.453592 kg
- 10 lb = 4.53592 kg
- 50 lb = 22.6796 kg
- 100 lb = 45.3592 kg
- 250 lb = 113.398 kg
Gym plates
A standard 45 lb plate is 20.41 kg, close to the 20 kg Olympic plate but not the same. A bar loaded with four 45 lb plates plus a 45 lb bar (225 lb) is 102.06 kg.
Common mistakes
Dividing by 2 as a shortcut. It overshoots by 10%: 200 lb ÷ 2 = 100 kg, but the real answer is 90.7 kg.
Confusing avoirdupois with troy pounds. Precious metals use troy ounces; body weight and groceries use avoirdupois.
For ounces and grams, see ounces to grams. For the reverse, use kg to pounds.