Convert between metric and imperial weight units instantly.
Weight and mass conversion is essential in cooking, shipping, science, fitness, medicine, and countless other fields. Whether you are following an international recipe that lists ingredients in grams, shipping a package and need to know the weight in pounds, tracking your body weight in different units, or calculating dosages in milligrams, this converter provides instant, accurate results across all commonly used weight units.
The metric system measures mass in grams and kilograms. Like all metric measurements, it follows a decimal structure: there are 1,000 milligrams in a gram, 1,000 grams in a kilogram, and 1,000 kilograms in a metric ton (also called a tonne). The gram was originally defined as the mass of one cubic centimeter of water at 4 degrees Celsius. The kilogram is the base unit of mass in the International System of Units (SI) and was redefined in 2019 in terms of the Planck constant, replacing the old physical prototype that had been stored in Paris since 1889.
The imperial system primarily uses ounces and pounds. There are 16 ounces in a pound. The stone, equal to 14 pounds, is commonly used in the United Kingdom and Ireland for body weight. The US customary ton (short ton) equals 2,000 pounds, while the British imperial ton (long ton) equals 2,240 pounds. This converter uses the metric ton (1,000 kg or approximately 2,204.6 pounds), which is the international standard for large-scale measurements.
The fundamental relationship between metric and imperial weight is that one pound equals exactly 453.59237 grams, or approximately 0.4536 kilograms. One ounce equals approximately 28.3495 grams. One kilogram equals approximately 2.20462 pounds. One stone equals 6.35029 kilograms. These conversion factors are internationally standardized and form the basis for all cross-system weight conversions.
| From | To | Multiply by |
|---|---|---|
| Pounds | Kilograms | 0.45359 |
| Kilograms | Pounds | 2.20462 |
| Ounces | Grams | 28.3495 |
| Grams | Ounces | 0.03527 |
| Stone | Kilograms | 6.35029 |
| Stone | Pounds | 14 |
Weight conversions are needed in many everyday situations. International cooking and baking often requires converting between grams and ounces or cups. Shipping companies use both pounds and kilograms depending on the carrier and destination. Healthcare professionals may need to convert patient weights between kilograms and pounds for medication dosing, as most pharmaceutical calculations use metric units. Fitness enthusiasts tracking macronutrients and body weight frequently switch between systems. Manufacturing and engineering rely on precise weight measurements across different unit systems when working with international suppliers or standards.
For rough estimates, you can use these mental shortcuts: to convert kilograms to pounds, multiply by 2.2 (so 70 kg is about 154 lb). To convert pounds to kilograms, divide by 2.2 (so 150 lb is about 68 kg). For ounces to grams, multiply by 28 (so 4 oz is about 112 g). One stone is 14 pounds, so a person weighing 10 stone weighs 140 pounds or about 63.5 kilograms. These approximations are useful for quick calculations when exact precision is not required.
There are approximately 453.592 grams in one pound, which means one pound equals about 0.4536 kilograms.
There are exactly 16 ounces in one pound.
One stone equals 14 pounds (approximately 6.35 kilograms). It is commonly used in the UK and Ireland for body weight.
Multiply the kilogram value by 2.20462. For a quick estimate, multiply by 2.2. For example, 70 kg is about 154 pounds.
Mass measures the amount of matter and stays constant. Weight is the force of gravity on that mass and varies by location. On Earth they are used interchangeably in everyday language.