Mass Calculator
PrintMass of Common Entities
| Entity | Mass (kg) |
|---|---|
| Milky Way Galaxy | \(1.15 \times 10^{42}\) |
| Sun | \(1.989 \times 10^{30}\) |
| Earth | \(5.9722 \times 10^{24}\) |
| Moon | \(7.3477 \times 10^{22}\) |
| Proton | \(1.6726 \times 10^{-27}\) |
| Electron | \(9.109 \times 10^{-31}\) |
In physics and engineering, mass is defined as the quantitative measure of matter contained within an physical object. It represents an object’s intrinsic resistance to acceleration when a net force is applied (known as inertia). While volume measures spatial size, objects with large volumes do not necessarily have large masses—an inflated balloon occupies far more volume than a solid silver sphere, yet possesses a fraction of its mass.
Our free online Mass Calculator calculates total mass using the classic density-volume relationship:
Mass (m) = Density (ρ) × Volume (V)
Input any material density (in kg/m³, g/cm³, lb/ft³, or lb/gal) alongside container volume (m³, liters, ft³, or gallons) to calculate mass across metric, imperial, and specialized laboratory units.
Mass vs. Weight: Core Physics Differences
Although the terms “mass” and “weight” are often used interchangeably in everyday language, they represent distinctly different physical quantities in physics:
| Property | Mass (m) | Weight (W) |
|---|---|---|
| Fundamental Definition | Amount of matter and measure of inertia. | Force exerted on a mass by a gravitational field. |
| Nature of Quantity | Intrinsic property (constant everywhere in the universe). | Extrinsic property (varies depending on local gravity). |
| SI Base Unit | Kilogram (kg) | Newton (N = kg·m/s²) |
| Governing Equation | m = F ÷ a or m = ρ × V |
W = m × g |
| Effect in Freefall / Orbit | Retains 100% of mass. | Becomes zero (apparent weightlessness). |
Earth vs. Moon Gravity Example
The gravitational acceleration on the Moon (g ≈ 1.62 m/s²) is roughly one-sixth of Earth’s surface gravity (g ≈ 9.81 m/s²):
- An astronaut with a mass of 70 kg on Earth has an Earth weight of
70 × 9.81 = 686.7 Newtons (154 lbs-force). - On the Moon, the astronaut’s mass remains exactly 70 kg, but their Moon weight drops to
70 × 1.62 = 113.4 Newtons (25.5 lbs-force).
The Three Classifications of Mass in Physics
Theoretical physics categorizes mass into three operational definitions:
| Mass Classification | Physical Definition | Key Governing Law |
|---|---|---|
| Inertial Mass | Measures an object’s resistance to change in velocity when subjected to an external force. | Newton’s Second Law: F = m·a |
| Active Gravitational Mass | Measures the magnitude of the gravitational attraction field exerted by an object on surrounding matter. | Newton’s Universal Gravitation: F = G·(m1·m2) ÷ r² |
| Passive Gravitational Mass | Measures the gravitational force experienced by an object when placed inside an external gravitational field. | Gravitational Force: Fg = m·g |
*Note: Einstein’s Equivalence Principle establishes that inertial mass and gravitational mass are strictly equivalent in all physical measurements.
Standard Units of Mass & Conversion Factors
Below is a quick-reference table of common mass units converted to the SI base unit (kilogram):
| Mass Unit | Abbreviation | Kilogram Equivalent (SI) | Pound Equivalent (Avoirdupois) |
|---|---|---|---|
| Kilogram (SI Base) | kg | 1.0 kg | 2.20462 lbs |
| Gram | g | 0.001 kg | 0.00220462 lbs |
| Metric Ton (Tonne) | t | 1,000 kg | 2,204.62 lbs |
| Pound (Avoirdupois) | lb | 0.45359237 kg | 1.0 lb |
| Ounce (Avoirdupois) | oz | 0.0283495 kg | 0.0625 lbs (1/16 lb) |
| Slug (Imperial Mass Unit) | slug | 14.5939 kg | 32.174 lbs |
| Grain | gr | 0.0000647989 kg | 0.000142857 lbs (1/7000 lb) |
To look up material density values before computing mass, visit our Density Calculator. To determine three-dimensional container sizes, use our Volume Calculator. For general unit conversions, explore our Conversion Calculator.
Frequently Asked Questions (FAQ)
How do I calculate mass when density and volume are known?
To calculate mass, multiply the material density (ρ) by the object’s volume (V):
Mass = Density × Volume
Ensure units match before multiplying (e.g., density in kg/m³ multiplied by volume in m³ yields mass in kilograms).
What is a slug in imperial physics units?
A slug is the imperial unit of mass in the foot-pound-second (FPS) system. One slug is defined as the mass that accelerates at 1 foot/second² when subjected to a force of 1 pound-force (lbf). One slug equals approximately 14.5939 kilograms (32.174 lbs).
Can an object be weightless while still having mass?
Yes. Astronauts orbiting Earth in the International Space Station (ISS) experience apparent weightlessness because they are in continuous freefall alongside their spacecraft. However, their mass remains 100% unchanged, and pushing against a heavy object in space still requires force to overcome its inertia ($F = ma$).
How is the kilogram defined in the modern SI system?
Since May 2019, the kilogram is no longer defined by a physical prototype cylinder in France. It is officially defined by fixing the numerical value of Planck’s constant (h = 6.62607015 × 10-34 J·s) using a Kibble balance.