What is the mass?
Type a density and a volume, a force and an acceleration, or a weight, and the mass calculator gives the mass in kilograms, grams, pounds and ounces.
- Mass (lb)
- 4.40925
The mass is 4.40925 lb (2 kg).
- Mass (kg)
- 2
- Mass (g)
- 2,000
- Mass (oz)
- 70.5479
Mass (lb): 4.40925. The mass is 4.40925 lb (2 kg).
How to calculate
Finds a mass from density and volume (m = ρV), from a force and an acceleration (m = F ÷ a), or from a weight and the gravity (m = W ÷ g), in kilograms, grams and pounds.
Example with the default inputs (Find the mass from Density × volume, Density 62.4279605761446 lb/ft³, Volume 0.528344104716297 gal): The mass is 4.40925 lb (2 kg).
Method: m = ρ × V; m = F ÷ a; m = W ÷ g.
- Density × volume assumes the material is the same all through the object (an average density otherwise).
- Force ÷ acceleration uses the net force; weight ÷ gravity uses the gravity where the object is weighed.
- Exact unit sizes: 1 lb = 0.45359237 kg; 1 ft³ = 0.028316846592 m³; 1 gal = 3.785411784 L; 1 lbf = 4.4482216152605 N; 1 kgf = 9.80665 N.
Worked examples
Each example is checked against the calculator on every build.
- Find the mass from Density × volume, Density 62.43 lb/ft³, Volume 0.5283 gal gives Mass (kg) 2, Mass (g) 2,000, Mass (lb) 4.409245.Source: OpenStax, University Physics Volume 1, §14.1 Fluids, Density, and Pressure (ρ = m ÷ V), https://openstax.org/books/university-physics-volume-1/pages/14-1-fluids-density-and-pressure
- Find the mass from Force ÷ acceleration, Net force 2.248 lbf, Acceleration 2, Acceleration unit m/s² gives Mass (kg) 5.Source: OpenStax, University Physics Volume 1, §5.3 Newton’s Second Law (F = m a), https://openstax.org/books/university-physics-volume-1/pages/5-3-newtons-second-law
- Find the mass from Weight ÷ gravity, Weight 1 lbf, Gravity (m/s²) 9.80665 gives Mass (lb) 1, Mass (kg) 0.453592, Mass (oz) 16.Source: OpenStax, University Physics Volume 1, §5.4 Mass and Weight (w = m g), https://openstax.org/books/university-physics-volume-1/pages/5-4-mass-and-weight
- Find the mass from Density × volume, Density 62.4 lb/ft³, Volume 74.81 gal gives Mass (lb) 624.Source: OpenStax, University Physics Volume 1, §14.1 Fluids, Density, and Pressure (ρ = m ÷ V), https://openstax.org/books/university-physics-volume-1/pages/14-1-fluids-density-and-pressure
How it works
Pick how to find the mass m:
- Density × volume: m = ρ × V.
- Force ÷ acceleration: m = F ÷ a, where F is the net force and a the acceleration it gives (a in m/s², ft/s² × 0.3048, or g × 9.80665).
- Weight ÷ gravity: m = W ÷ g, with g in m/s² (9.80665 on Earth by default).
The mass shows in kilograms, grams (kg × 1,000), pounds (kg ÷ 0.45359237) and ounces (pounds × 16).
Unit sizes: 1 g/cm³ = 1 g/mL = 1 kg/L = 1,000 kg/m³; 1 lb/ft³ = 0.45359237 ÷ 0.028316846592 kg/m³; 1 lb/in³ = 0.45359237 ÷ 0.000016387064 kg/m³; 1 lb/gal = 0.45359237 ÷ 0.003785411784 kg/m³. 1 L = 0.001 m³; 1 mL = 1 cm³ = 10⁻⁶ m³; 1 ft³ = 0.028316846592 m³; 1 in³ = 0.000016387064 m³; 1 gal = 0.003785411784 m³; 1 yd³ = 0.764554857984 m³. 1 kN = 1,000 N; 1 lbf = 4.4482216152605 N; 1 kgf = 9.80665 N; 1 dyn = 10⁻⁵ N.
Exact arithmetic. Each value is read as the exact decimal you typed, in its unit, and every unit size is exact, so the mass is an exact fraction until it is rounded for display.
Output format. Every value shows 6 significant figures. The headline is in pounds in US units and kilograms in Metric.
Assumptions
- The density is the average density of the whole object.
- Density more than 0 and at most 10⁶ kg/m³; volume more than 0 and at most 10⁹ m³; force and weight more than 0 and at most 10¹² N; acceleration 0.000001 to 10⁹ in its unit; gravity 0.001 to 1,000 m/s².
Worked examples by hand
Two liters of water. m = 1,000 kg/m³ × 0.002 m³ = 2 kg = 2,000 g = 2 ÷ 0.45359237 = 4.40925 lb.
10 N at 2 m/s². m = 10 ÷ 2 = 5 kg.
A weight of 1 lbf on Earth. m = 4.4482216152605 N ÷ 9.80665 m/s² = 0.45359237 kg = 1 lb = 16 oz.
10 ft³ at 62.4 lb/ft³. m = 62.4 × 10 = 624 lb.
Other questions people ask
How do you calculate mass from density and volume?
Multiply them: m = ρ × V. Two liters of water (0.002 m³) at 1,000 kg/m³ has a mass of 1,000 × 0.002 = 2 kg, or 4.41 lb.
How do you find mass from force and acceleration?
Rearrange Newton’s second law F = m a to m = F ÷ a. A net force of 10 N that gives an acceleration of 2 m/s² acts on a mass of 5 kg.
How do you find mass from weight?
Divide the weight by the acceleration of gravity: m = W ÷ g. On Earth g = 9.80665 m/s², so a weight of 98.0665 N is a mass of 10 kg. On the Moon (g ≈ 1.62 m/s²) the same mass weighs only about 16.2 N.
What is the difference between mass and weight?
Mass is how much matter an object has, in kilograms; it is the same everywhere. Weight is the force of gravity on that mass, in newtons or pounds-force, and it changes with the gravity.
Why does 1 lbf of weight give 1 lb of mass?
The pound-force is defined as the weight of 1 lb of mass at standard gravity: 0.45359237 kg × 9.80665 m/s² = 4.4482216152605 N. With g = 9.80665, any weight in lbf is the same number of pounds of mass.