A measure of how much matter is in an object.
This gold bar has a mass of 1 kilogram (about 2.2 pounds).
Mass is commonly measured by how much something weighs. But weight is caused by gravity, so your weight on the Moon is less than here on Earth, while the mass stays the same.
Mass is usually measured in:
• grams, kilograms and tonnes in Metric,
• ounces, pounds and tons in US units.
See: Weight