Understanding Weight Units: kg, lb, stone, oz explained

Weight and mass units vary by country and context. Understanding all the common units helps with international travel, cooking, fitness, and shipping.

Kilogram (kg): The base unit of mass in the metric system, used by most countries. Originally defined by a physical platinum-iridium cylinder, it is now defined by fundamental physical constants. 1 kg = 1,000 grams.

Pound (lb): The primary weight unit in the United States. 1 lb = 16 ounces = 0.4536 kg. The symbol "lb" comes from the Latin "libra." Body weight, food packaging, and shipping in the US all use pounds.

Stone (st): Used primarily in the UK and Ireland for human body weight. 1 stone = 14 lbs = 6.35 kg. A person described as "11 stone 4" weighs 158 lbs or 71.7 kg. Stone is rarely used outside of body weight context.

Ounce (oz): The smaller imperial unit. 1 oz = 28.35 g. Used for small food portions, postal weights, and precious metals (troy ounce, which is 31.1 g — different from the standard ounce).

Gram (g): The metric small-unit. 1 g = 0.035 oz. A paperclip weighs about 1 g. Food nutrition labels use grams internationally.

Metric ton (t): 1,000 kg or approximately 2,204.6 lbs. Used for industrial quantities, shipping containers, and large-scale agriculture.

Use Tooler's Weight Converter for instant conversions between all these units.