Mass Calculator

What Is Mass?

Mass is a fundamental property of matter that measures the amount of material in an object. It determines how much an object resists acceleration (a property called inertia) and how strongly it is attracted by gravity.

Mass is measured in kilograms (kg) in the International System of Units (SI). Unlike weight, mass does not change with location — a 70 kg person has a mass of 70 kg whether they are on Earth, the Moon, or floating in space.

How to Calculate Mass

Mass from Force and Acceleration

Using Newton's second law (F = ma), you can rearrange to solve for mass:

Where m is mass in kg, F is force in newtons, and a is acceleration in m/s².

Mass from Density and Volume

If you know the density of the material and the volume of the object:

Where ρ is density (kg/m³) and V is volume (m³). This is useful for calculating the mass of liquids, gases, or solid objects with known dimensions. You can also use our density calculator to find or verify density values.

Mass vs. Weight

Mass and weight are often confused but are fundamentally different. Mass measures how much matter an object contains (kg). Weight is the gravitational force on that mass (N). Weight = mass × g. On Earth (g = 9.81 m/s²), a 10 kg object weighs 98.1 N. On the Moon (g = 1.62 m/s²), the same object weighs only 16.2 N — but its mass is still 10 kg.