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Density
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Sources & Methodology
Density values verified against NIST Standard Reference Database and Engineering Toolbox material properties.
NIST SP 811 — SI Units and Conversions
Official NIST reference for SI unit definitions and conversion factors used for mass, volume, and density unit conversions in this calculator.
Engineering Toolbox — Density of Solids
Comprehensive reference database for material densities at standard conditions used to identify materials from calculated density values.
Methodology: Density d = m/V. Volume V = m/d. Mass m = d×V. All inputs converted to SI base units (kg and m³) before calculation. Density converted to g/cm³ for display (1 g/cm³ = 1000 kg/m³ = 1 kg/L). Mass conversions: 1 lb = 453.592 g, 1 oz = 28.3495 g. Volume conversions: 1 L = 1000 cm³, 1 ft³ = 28316.8 cm³, 1 in³ = 16.3871 cm³.
⏱ Last reviewed: March 2026
How to Calculate Density — Formula & Material Reference
Density is a fundamental physical property that describes how much mass is packed into a given volume. It determines whether objects float or sink, how materials behave under stress, and is used across physics, chemistry, engineering, and everyday life.
The Density Formula
d = m / V m = d × V V = m / d
d = density (g/cm³, kg/m³) • m = mass (g, kg) • V = volume (cm³, m³, L)
Example 1 — Find density of aluminium block:
Mass = 2700 g, Volume = 1000 cm³ → d = 2700/1000 = 2.70 g/cm³ (aluminium ✓)
Example 2 — Find volume of 1 kg of water:
Mass = 1000 g, Density = 1.0 g/cm³ → V = 1000/1.0 = 1000 cm³ = 1 litre
Example 1 — Find density of aluminium block:
Mass = 2700 g, Volume = 1000 cm³ → d = 2700/1000 = 2.70 g/cm³ (aluminium ✓)
Example 2 — Find volume of 1 kg of water:
Mass = 1000 g, Density = 1.0 g/cm³ → V = 1000/1.0 = 1000 cm³ = 1 litre
Density of Common Materials
| Material | Density (g/cm³) | Density (kg/m³) | Floats on Water? |
|---|---|---|---|
| Air (sea level, 20°C) | 0.00120 | 1.20 | Yes |
| Cork | 0.12 | 120 | Yes |
| Wood (pine) | 0.50 | 500 | Yes |
| Ice (0°C) | 0.917 | 917 | Yes |
| Water (4°C) | 1.000 | 1000 | — |
| Seawater | 1.025 | 1025 | No |
| Concrete | 2.30 | 2300 | No |
| Aluminium | 2.70 | 2700 | No |
| Iron/Steel | 7.87 | 7870 | No |
| Copper | 8.96 | 8960 | No |
| Lead | 11.34 | 11340 | No |
| Gold | 19.30 | 19300 | No |
💡 Density conversion shortcut: g/cm³ and g/mL are identical units. To convert g/cm³ to kg/m³, multiply by 1000. To convert kg/m³ to g/cm³, divide by 1000. Water at 4°C = 1.000 g/cm³ = 1000 kg/m³ = 62.43 lb/ft³. Specific gravity equals density in g/cm³ numerically (dimensionless ratio to water).
Unit Conversion Table for Density
| g/cm³ | kg/m³ | kg/L | lb/ft³ | lb/in³ |
|---|---|---|---|---|
| 1 | 1000 | 1 | 62.43 | 0.03613 |
| 2.70 | 2700 | 2.70 | 168.6 | 0.09754 |
| 7.87 | 7870 | 7.87 | 491.3 | 0.2842 |
| 19.30 | 19300 | 19.30 | 1205 | 0.6972 |
Frequently Asked Questions
Density = Mass / Volume (d = m/V). Rearranged: Volume = Mass / Density, and Mass = Density × Volume. For example, 500 g of a material occupying 250 cm³ has density = 500/250 = 2.0 g/cm³, which is close to aluminium (2.70 g/cm³). The SI unit of density is kg/m³, but g/cm³ (= g/mL) is commonly used for solids and liquids.
Multiply g/cm³ by 1000 to get kg/m³. Water = 1.0 g/cm³ = 1000 kg/m³. Steel = 7.85 g/cm³ = 7850 kg/m³. The conversion arises because 1 m³ = 10⁶ cm³ and 1 kg = 1000 g, so the ratio is 10⁶/1000 = 1000. To go back, divide by 1000.
Pure water at 4°C = 1.000 g/cm³ = 1000 kg/m³ = 62.43 lb/ft³. At room temperature (20°C) = 0.9982 g/cm³. At boiling (100°C) = 0.9584 g/cm³. Ice = 0.917 g/cm³ (less than water, so ice floats). Seawater = 1.025 g/cm³ due to dissolved salts.
Measure the mass (using a scale) and volume (using water displacement or dimensions) of the unknown material. Calculate d = m/V. Compare to a density table: aluminium = 2.70 g/cm³, iron = 7.87 g/cm³, gold = 19.30 g/cm³, copper = 8.96 g/cm³. If your calculation gives 19.3 g/cm³, the material is almost certainly gold. This method is used in geology, archaeology, and materials testing.
Ice has density 0.917 g/cm³, which is less than liquid water (1.000 g/cm³ at 4°C). By Archimedes’ principle, objects float when their density is less than the fluid they’re in. The reason ice is less dense than water is unusual: water molecules form a hexagonal crystal lattice in ice that takes up more space than the hydrogen-bonded network in liquid water. Most substances are denser as solids than as liquids.
Specific gravity (SG) = material density / water density. Since water = 1.0 g/cm³, specific gravity numerically equals density in g/cm³. Gold SG = 19.3, aluminium SG = 2.70, ice SG = 0.917. SG < 1 = floats, SG > 1 = sinks. Specific gravity is dimensionless and the same in all unit systems, making it easy to compare materials internationally.
Use Archimedes’ water displacement method: (1) Fill a graduated cylinder with water, note the volume V1. (2) Submerge the object, note the new volume V2. (3) Object volume = V2 − V1. Then weigh the object to get mass. Density = mass / (V2−V1). This works for any object that does not dissolve in water and is not hollow.
Osmium is the densest naturally occurring element at 22.59 g/cm³ (22590 kg/m³), closely followed by iridium at 22.56 g/cm³. Both are transition metals in the platinum group. For comparison, gold = 19.30 g/cm³, lead = 11.34 g/cm³, iron = 7.87 g/cm³. The least dense solid element is lithium at 0.534 g/cm³, which floats on water and is light enough to be cut with a knife.
Engineers use density to: calculate structural load (mass = density × volume), select lightweight materials for aerospace (aluminium 2.70, titanium 4.50 vs steel 7.85 g/cm³), design buoyancy systems for ships and submarines, calculate fuel mass in aircraft (jet fuel ≈ 0.80 g/cm³), model concrete and soil bearing capacity in civil engineering, and determine specific gravity of drilling fluids in oil and gas operations.
True (or absolute) density = mass / solid volume (excludes any pores or voids). Bulk density = mass / total volume including pores and air gaps. For example, loose sand has bulk density around 1.4–1.7 g/cm³ but its mineral grains have true density of about 2.65 g/cm³. Bulk density matters in agriculture, construction (concrete mix design), powder technology, and shipping weight calculations.
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