Why weight units vary so much
Weight conversions come up constantly in daily life: recipes measured in grams or ounces, shipping quoted in kilograms or pounds, and body weight tracked in pounds, kilograms, or — especially in the UK and Ireland — stone. This tool converts between all of them instantly, so you don't have to remember the conversion factors yourself.
Where each unit is commonly used
- Grams and kilograms — cooking, science, most of the world's everyday weight measurements
- Ounces and pounds — US recipes, body weight, retail packaging
- Stone — everyday body weight in the UK and Ireland (1 stone = 14 pounds)
- Tonnes — freight, shipping, and industrial quantities
Frequently asked questions
Why is a stone equal to 14 pounds?
The stone is a historical British unit that was standardized at 14 pounds; it's still the everyday way body weight is expressed in the UK and Ireland, even though the metric kilogram is used for most other measurements there.
Is a kilogram a unit of weight or mass?
Technically mass — but in everyday conversions like these, "weight" and "mass" are used interchangeably, since we're comparing how units relate to each other rather than measuring gravitational force.