Density Converter — Convert Density Units Instantly
Free online density converter. Convert between g/cm³, kg/m³, lb/ft³, and other density units with instant results.
Try the free calculator
Put these formulas into practice with our instant, step-by-step Density & Concentration Calculator.
TL;DR
Density equals mass divided by volume (ρ = m/V). The most common density units are g/cm³ (lab work), kg/m³ (SI standard), and lb/ft³ (US engineering). Converting between these requires multiplying by the appropriate factor: 1 g/cm³ = 1,000 kg/m³ = 62.428 lb/ft³. Use our converter for instant, accurate results across all standard density units.
Free — no sign-up required
Density is the mass of a substance per unit volume, commonly expressed in grams per cubic centimeter, kilograms per cubic meter, or pounds per cubic foot. A density converter allows you to translate a measurement from one unit system to another instantly, which is essential in engineering, material science, cooking, and any field where substances are measured by their compactness. Understanding density and how to convert between units is fundamental for accurate calculations in science and industry.
What Is Density?
Density describes how tightly matter is packed within a given volume. A material with high density, like lead (11,340 kg/m³), has a lot of mass in a small space. A material with low density, like cork (240 kg/m³), has very little mass for its size. This property determines whether objects float or sink in water, how heat transfers through materials, and how engineers select substances for specific applications.
The SI unit for density is kilograms per cubic meter (kg/m³), but grams per cubic centimeter (g/cm³) is common in laboratory settings, and pounds per cubic foot (lb/ft³) is frequently used in American engineering contexts. Being able to convert between these units ensures that data from different sources can be compared and applied correctly.
Quick Definition
Density (ρ) is the mass (m) of a substance divided by its volume (V). The formula is ρ = m/V. Higher density means more mass per unit volume. Density determines buoyancy, heat transfer, and material selection in engineering.
The Density Formula
The fundamental formula for density is straightforward:
If you have 500 grams of a substance occupying 200 cubic centimeters, the density is 500 / 200 = 2.5 g/cm³. To convert this to kg/m³, multiply by 1,000 to get 2,500 kg/m³. The formula works regardless of which units you use, as long as you apply the correct conversion factors.
Density can also be expressed using specific gravity, which is the ratio of a material's density to the density of water at 4°C (1,000 kg/m³). A specific gravity of 2.5 means the material is 2.5 times denser than water. This dimensionless quantity is useful for comparing materials without worrying about unit systems.
Common Density Units
| Unit | Symbol | System | Common Use |
|---|---|---|---|
| Kilograms per cubic meter | kg/m³ | SI | Engineering, physics, construction |
| Grams per cubic centimeter | g/cm³ | CGS | Laboratory, chemistry, geology |
| Pounds per cubic foot | lb/ft³ | Imperial | US construction, HVAC, mining |
| Pounds per cubic inch | lb/in³ | Imperial | Metal density, machining |
| Kilograms per liter | kg/L | Metric | Liquid density, fuel, chemicals |
Conversion Factors and Methods
Converting between density units requires multiplying by the appropriate conversion factor. The key relationships are:
1 g/cm³ = 1,000 kg/m³
1 g/cm³ = 62.428 lb/ft³
1 kg/m³ = 0.06243 lb/ft³
1 lb/ft³ = 16.018 kg/m³
1 lb/ft³ = 0.01602 g/cm³
To convert from g/cm³ to kg/m³, multiply by 1,000. To convert from kg/m³ to lb/ft³, multiply by 0.06243. To convert from lb/ft³ to g/cm³, multiply by 0.01602. These factors are derived from the relationships between mass units (kg, g, lb) and volume units (m³, cm³, ft³).
Worked Conversion Examples
Example 1: Water — g/cm³ to kg/m³
Water has a density of 1.0 g/cm³. Convert to kg/m³: 1.0 × 1,000 = 1,000 kg/m³.
Example 2: Concrete — kg/m³ to lb/ft³
Concrete has a density of 2,400 kg/m³. Convert to lb/ft³: 2,400 × 0.06243 = 149.8 lb/ft³.
Example 3: Steel — lb/in³ to g/cm³
Steel has a density of 0.284 lb/in³. Convert to g/cm³: 0.284 × 27.68 = 7.86 g/cm³.
Specific Gravity and Relative Density
Specific gravity (SG) is the ratio of a material's density to the density of water at 4°C. Since water's density is 1,000 kg/m³ or 1.0 g/cm³, the specific gravity numerically equals the density in g/cm³. A material with SG = 2.5 has a density of 2.5 g/cm³.
Specific gravity is dimensionless, making it useful for comparing materials across different unit systems. In the wine and beverage industry, specific gravity measures sugar content. In geology, it identifies minerals. In battery maintenance, it indicates electrolyte charge level. Converting between density and specific gravity is trivial when using water as the reference.
Density of Common Materials
| Material | g/cm³ | kg/m³ | lb/ft³ |
|---|---|---|---|
| Water (4°C) | 1.000 | 1,000 | 62.43 |
| Aluminum | 2.700 | 2,700 | 168.5 |
| Iron | 7.874 | 7,874 | 491.5 |
| Copper | 8.960 | 8,960 | 559.0 |
| Gold | 19.320 | 19,320 | 1,206.0 |
| Lead | 11.340 | 11,340 | 707.6 |
Applications of Density Conversion
Density conversion is critical in manufacturing where material specifications may arrive in one unit system but production equipment operates in another. In the oil and gas industry, density measurements determine the type and quality of crude oil. Light crude (below 870 kg/m³) is more valuable than heavy crude (above 920 kg/m³) because it yields more gasoline and diesel.
In construction, the density of concrete and steel affects structural calculations. Lightweight concrete (1,200–1,800 kg/m³) is used for insulation, while standard concrete (2,300–2,500 kg/m³) provides structural strength. In cooking and nutrition, the density of ingredients affects portion sizing and recipe scaling. A density converter ensures accuracy across all these contexts.
Frequently Asked Questions
What is the density of water?
Water has a density of 1,000 kg/m³ or 1.0 g/cm³ at 4°C, which is its maximum density. At room temperature (20°C), water density is approximately 998 kg/m³. This value serves as the reference for specific gravity calculations.
How do I convert g/cm³ to kg/m³?
Multiply by 1,000. Since 1 gram = 0.001 kilograms and 1 cubic centimeter = 0.000001 cubic meters, the conversion factor is 1,000. For example, 2.7 g/cm³ = 2,700 kg/m³.
What is specific gravity?
Specific gravity is the ratio of a material's density to the density of water at 4°C. It is dimensionless and numerically equal to density in g/cm³. A specific gravity of 7.86 means the material is 7.86 times denser than water.
Why do different industries use different density units?
Historical and practical reasons. SI uses kg/m³, laboratories prefer g/cm³ for smaller numbers, and US industries use lb/ft³ for compatibility with other imperial measurements. A converter bridges these systems.
Does density change with temperature?
Yes, most materials expand when heated, decreasing density. Water is unusual — it is densest at 4°C and becomes less dense as it cools toward freezing. This is why ice floats.
How does density affect buoyancy?
An object floats if its density is less than the fluid it is immersed in. A ship floats because its average density (including air inside) is less than water, even though steel is much denser than water.
What is the densest naturally occurring element?
Osmium, at approximately 22,590 kg/m³ (22.59 g/cm³), is the densest naturally occurring element. It is used in fountain pen tips, electrical contacts, and other applications requiring extreme hardness and density.
Can I use this converter for liquids and gases?
Yes, the converter works for any substance. Liquids like oil (800–950 kg/m³) and mercury (13,546 kg/m³) and gases like air (1.225 kg/m³) can all be converted between density units.