Weight Conversion.

Multiply pounds by 0.4536 to get kilograms. For example, 150 pounds is 68.04 kg, and 200 pounds is 90.72 kg. For a quick mental estimate, divide pounds by 2 and subtract 10%. So 180 lbs divided by 2 is 90, minus 9, gives you roughly 81 kg (actual: 81.65 kg).

One stone equals exactly 14 pounds (6.35 kg). Stones are commonly used in the UK and Ireland for body weight. A person weighing 154 pounds is 11 stone, and 170 pounds is 12 stone 2 pounds. To convert stones to pounds, multiply by 14 and add any remaining pounds.

One avoirdupois ounce (the standard ounce for everyday use) equals 28.3495 grams. Note that a troy ounce, used for precious metals like gold, is heavier at 31.1035 grams. To convert grams to ounces, divide by 28.35. A 100-gram chocolate bar weighs about 3.53 ounces.