This converter makes instant conversions between common units of weight including milligrams, grams, kilograms, tons, pounds, and ounces. To use this converter, please select the units and provide a value to convert. The converter will make conversions as the value is being typed in.
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Weight as a measurement
Weight is a measurement of the force that acts on an object due to gravity. Weight and mass are often used interchangeably, though they are actually different concepts physically. The mass of an object does not change regardless of where the object is. Its weight however, does, since the weight of an object is a function of the object's mass as well as the force of gravity. Specifically, the weight of an object is the product of the object's mass multiplied by the force of gravity. On the moon for example, a person who weighs 120 pounds on Earth would weigh only around 20 pounds, since the gravitational force on the moon is approximately 1/6 that on Earth. Their mass however, would remain the same on both the moon and on Earth, since mass is a measure of the amount of matter in an object, where matter can be loosely described as any substance that has mass and takes up volume. For the purposes of this converter, we will use the definition of weight that is equivalent to mass, rather than its physical definition.
There are many different measurements of weight used in both the International System of Units (SI) and US customary system. The SI unit of weight is the Newton, but since we are using mass for the purposes of this calculator, the SI base unit of mass is the kilogram. In SI, each unit of measurement has a base unit. In the case of mass, it is the kilogram. Prefixes are used in SI to denote some power of 10 by which a given unit of measurement differs from the base unit. For example, a kilogram, in which the prefix is "kilo" is equal to 1,000 grams. The kilogram is slightly different in terms of an SI unit since most other units, such as the meter, use the base unit of meter. If this same pattern were carried through for weight (mass), then the SI unit of mass should actually be the gram. This however, is not the case.
In the US customary system of measurement, weight is not measured relative to some base unit, as it is in SI. Simply put, the relationship between each unit of weight is something that needs to be memorized in order to do calculations by hand. Below are a few examples of common units of weight used in both SI and the US customary systems:
1 kilogram = 2.20462262185 pounds
1 kilogram = 1,000 grams
1 pound = 16 ounces
1 metric ton = 1,000 kg
1 ounce = 28.349523125 grams