Weight and Mass Unit Conversion Guide
Weight (technically mass in everyday usage) is measured differently across countries and contexts. Most of the world uses kilograms (metric), while the US uses pounds and ounces (imperial). The UK uses a mix — kilograms officially but stones and pounds colloquially for body weight. Understanding conversion factors is essential for travel, cooking, medicine, and science.
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Formula
Weight Converter
Convert weight between kilograms, pounds, grams, ounces, and stones.
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Worked Example
Given:
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FAQs
What is the difference between mass and weight?
Mass is the amount of matter in an object (kg) and is constant regardless of location. Weight is the gravitational force on that mass (Newtons) and changes with gravity. In everyday usage, people say 'weight' when they mean mass. A person with 70 kg mass weighs less on the Moon despite having the same mass.
How many pounds are in a stone?
One stone equals exactly 14 pounds. This is a unit used in the UK and Ireland primarily for expressing body weight. A person weighing 11 stone 4 pounds weighs 11 × 14 + 4 = 158 pounds = 71.67 kg.
How does food nutrition labelling use weight units?
Nutrition facts panels express serving sizes and nutrient amounts in grams and milligrams in metric countries, and in grams alongside ounce equivalents in the US. Daily values are typically based on a 2,000 kcal diet. Vitamin and mineral amounts are often in micrograms (μg = 0.001 mg).