How to use it
- Choose what to find: density, mass or volume.
- Enter the known values and pick their units.
- Or pick a material to fill in its density.
- Read the result in kg/m³, g/cm³ and lb/ft³.
The density formula
Density (ρ) = mass (m) ÷ volume (V)
Rearranged: m = ρ × V and V = m ÷ ρ.
Density tells you how much mass is packed into a given space. The calculator accepts mass in pounds, ounces, grams, kilograms or metric tons and volume in cubic feet, cubic inches, US gallons, milliliters, liters or cubic meters. It shows density in kg/m³, g/cm³ and lb/ft³. Everything runs in your browser.
Examples
- Density: a 2 × 3 × 4 inch aluminum block (24 cu in ≈ 393 cm³) weighs about 1,062 g. Density = 1,062 / 393 ≈ 2.7 g/cm³, which matches aluminum.
- Mass: a 50-gallon water heater holds about 50 × 8.345 ≈ 417 lb of water.
- Volume: 1 kg of gold (19,300 kg/m³) takes up only about 51.8 cm³, a little more than 3 cubic inches.
Densities of common materials
| Material | kg/m³ | lb/ft³ |
|---|---|---|
| Air (68 °F, sea level) | 1.2 | 0.075 |
| Gasoline | 740 | 46 |
| Ice | 917 | 57 |
| Water | 1,000 | 62.4 |
| Concrete | 2,400 | 150 |
| Aluminum | 2,700 | 169 |
| Steel | 7,850 | 490 |
| Copper | 8,960 | 559 |
| Lead | 11,340 | 708 |
| Gold | 19,300 | 1,205 |
These are typical room-temperature values. Real materials vary with type, moisture, temperature and alloy.
Density unit conversions
- 1 g/cm³ = 1,000 kg/m³ = 1 kg/L
- 1 g/cm³ ≈ 62.43 lb/ft³ ≈ 8.345 lb/US gal
- 1 lb/ft³ ≈ 16.018 kg/m³
Water's density of 1 g/cm³ makes it a handy reference: anything denser sinks in water, anything less dense floats. Ice (0.917 g/cm³) floats with about 90% of its volume underwater.
Specific gravity
Specific gravity is a material's density divided by the density of water. It has no units. Steel's specific gravity is about 7.85, gasoline's about 0.74. Brewers use specific gravity to track fermentation, and jewelers use it to check precious metals: weigh the item in air and in water, and the ratio reveals its density.
Practical uses
- Shipping and lifting: estimate the weight of a steel plate, a water tank or a load of concrete before you move it.
- Cooking and science class: find the volume of a given mass of liquid.
- Checking materials: a measured density far from the expected value can reveal an alloy, air bubbles or a counterfeit.
To find a volume from dimensions first, use the volume calculator.
Common mistakes
- Mixing unit systems. Pounds divided by liters gives a strange unit; pick matching units or let the calculator convert.
- Weight vs. mass. In everyday US usage, pounds measure weight, which equals mass on Earth for these purposes.
- Bulk density. Gravel, sand, flour or mulch contain air between particles, so their bulk density is lower than the solid material's. Use the supplier's bulk figure for loads.
- Temperature. Liquids and gases expand when warm, so their density drops; water is densest at about 39 °F (4 °C).
- Hollow objects. A pipe or a boat has a much lower average density than its material, which is why a steel ship floats. Enter the total mass and the outside volume to get the average density.
Frequently asked questions
How do I calculate density?
Divide mass by volume. 1,062 g in 393 cm³ is about 2.7 g/cm³.
What is the density of water?
About 1,000 kg/m³ (1 g/cm³), or 62.4 lb/ft³ and 8.34 lb per US gallon at room temperature.
How do I find mass from density?
Multiply density by volume: m = ρ × V.
What units can I use?
Pounds, ounces, grams, kilograms and metric tons for mass; cubic feet, cubic inches, gallons, milliliters, liters and cubic meters for volume.
Why does ice float?
Ice is less dense than liquid water, about 917 versus 1,000 kg/m³.
Last updated: November 12, 2026