Weight conversion is essential in our globally connected world. Whether you're following a recipe with metric measurements, calculating shipping costs, monitoring your fitness progress, or working in science and engineering, understanding how to convert between weight units saves time and prevents errors.
The metric system uses kilograms as the standard unit of mass, while the United States commonly uses pounds. The stone, a traditional British unit, is still widely used in the UK and Ireland for measuring body weight.
Kilograms to Pounds: Multiply by 2.20462. Example: 70 kg = 154.32 lbs
Pounds to Kilograms: Multiply by 0.453592. Example: 150 lbs = 68.04 kg
Grams to Ounces: Multiply by 0.035274. Example: 500 g = 17.64 oz
Stones to Kilograms: Multiply by 6.35029. Example: 10 st = 63.50 kg
When I bought a vintage scale at an estate sale, it measured in stones. I had no idea how much 8 stones was in pounds until I used the converter—turns out it was 112 lbs! Now I can weigh myself the same way my grandparents did.
Weight is technically a measure of the force of gravity on an object's mass. Mass remains constant regardless of location, while weight changes based on gravitational pull. On the Moon, your weight would be about 16.5% of your Earth weight, but your mass would stay the same.
The kilogram was originally defined in 1795 as the mass of one liter of water. Today, it's defined by the Planck constant—a fundamental constant of quantum physics—making it extremely precise and stable.