Density is mass per unit volume: ρ = m/V. It tells you how much mass is packed into a given space. Water has a density of 1,000 kg/m³ (1 g/cm³). Steel is about 7,850 kg/m³, aluminum 2,700 kg/m³, and gold 19,300 kg/m³. Objects less dense than water float; denser objects sink.

What is the density of water?

The density of water is exactly 1,000 kg/m³ (1.000 g/cm³ or 1 kg/L) at 4°C. It decreases slightly at higher temperatures: at 20°C it is 998.2 kg/m³, and at 100°C it is 958.4 kg/m³. This is why warm water is less dense and rises. Sea water is slightly denser at about 1,025 kg/m³ due to dissolved salts.

What is the density of air?

The density of dry air at sea level (15°C, 101.325 kPa) is approximately 1.225 kg/m³. This varies with temperature, altitude and humidity. At high altitude the air is less dense, which is why jet engines produce less thrust and why mountain climbers need oxygen. Hot air (used in balloons) is less dense than cold air, creating buoyancy.

How do I convert g/cm³ to kg/m³?

Multiply by 1,000: 1 g/cm³ = 1,000 kg/m³. This is because 1 cm³ = 0.000001 m³ (10⁻⁶) and 1 g = 0.001 kg (10⁻³), so the ratio is 10⁻³/10⁻⁶ = 1,000. Example: iron has density 7.87 g/cm³ = 7,870 kg/m³. To go the other way (kg/m³ to g/cm³), divide by 1,000.

What materials have high density?

The densest common materials: osmium (22,590 kg/m³), iridium (22,560), platinum (21,450), gold (19,300), tungsten (19,250), lead (11,340), silver (10,500), copper (8,960), iron (7,870), aluminum (2,700), glass (2,500), concrete (2,300), water (1,000), wood (400–900). Osmium is the densest naturally occurring element.

How do I convert lb/ft³ to kg/m³?

Multiply by 16.0185: 1 lb/ft³ = 16.0185 kg/m³. This is because 1 pound = 0.4536 kg and 1 cubic foot = 0.02832 m³, so 1 lb/ft³ = 0.4536/0.02832 = 16.0185 kg/m³. Example: wood at 40 lb/ft³ = 40 × 16.0185 = 641 kg/m³. To convert kg/m³ to lb/ft³, divide by 16.0185.

What is specific gravity?

Specific gravity (SG) is the ratio of a substance’s density to the density of water (1,000 kg/m³). It is dimensionless — water has SG = 1, gold has SG = 19.3, aluminum has SG = 2.7. Objects with SG 1 sink. Specific gravity numerically equals density in g/cm³, making it convenient for quick mental calculations.

Density Converter

kg/m³ · g/cm³ · kg/L · lb/ft³ · lb/in³ · oz/in³ · t/m³

Convert density units instantly. Enter a value, select source and target units — all units update in the table below simultaneously. Click any row to set it as the conversion target.

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Water = 1,000 kg/m³ = 1 g/cm³ | 1 g/cm³ = 1,000 kg/m³ | 1 lb/ft³ = 16.018 kg/m³

All Density Units — Click a row to select as target

Unit	Name	Value

About Density Units

Density is a fundamental physical property that describes how much mass occupies a given volume: ρ = m/V. It determines whether objects float or sink, how materials behave under pressure, and is critical in engineering, chemistry, geology and fluid dynamics. Different fields use different units — SI science uses kg/m³, chemistry uses g/cm³, and engineering in the US uses lb/ft³.

🔬 SI and Metric Units

The SI unit for density is kg/m³ (kilograms per cubic metre). In chemistry and materials science, g/cm³ (grams per cubic centimetre) is more common — 1 g/cm³ = 1,000 kg/m³. Water at 4°C has the convenient density of exactly 1 g/cm³, making it the reference point for specific gravity. Tonne/m³ (t/m³) equals 1,000 kg/m³ and is used for bulk materials like ore and concrete. kg/L (kilograms per litre) also equals 1,000 kg/m³ since 1 litre = 1 dm³ = 0.001 m³.

🇺🇸 Imperial Units

US engineering uses lb/ft³ (pounds per cubic foot) — 1 lb/ft³ = 16.018 kg/m³. Denser materials are sometimes expressed in lb/in³ (pounds per cubic inch) — 1 lb/in³ = 27,679 kg/m³. Oz/in³ (ounces per cubic inch) is used in some manufacturing contexts — 1 oz/in³ = 1,729.9 kg/m³. The density of water in imperial units is approximately 62.4 lb/ft³ (at 4°C).

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Quick Density Reference

g/cm³ → kg/m³× 1,000 kg/m³ → g/cm³÷ 1,000 lb/ft³ → kg/m³× 16.018 kg/m³ → lb/ft³÷ 16.018 g/cm³ → kg/L= same value kg/m³ → kg/L÷ 1,000 lb/in³ → kg/m³× 27,679 kg/m³ → lb/in³÷ 27,679

Worked Examples

Aluminium (Engineering)

2.70 g/cm³

= 2,700 kg/m³ (× 1,000)
= 168.5 lb/ft³ (× 16.018 from g/cm³ × 62.4)
= 0.0975 lb/in³
SG = 2.70 (floats in mercury, sinks in water)

Sea Water (Oceanography)

1,025 kg/m³

= 1.025 g/cm³ (÷ 1,000)
= 64.0 lb/ft³ (÷ 16.018)
= 1.025 kg/L
2.5% denser than fresh water — explains why ships float higher in the ocean vs rivers

Gold (Precious Metals)

19.30 g/cm³

= 19,300 kg/m³ (× 1,000)
= 1,204.9 lb/ft³
= 0.6971 lb/in³
A 1 cm³ cube of gold weighs 19.3 g — same volume of water weighs only 1 g

Concrete (Construction)

2,300 kg/m³

= 2.30 g/cm³ (÷ 1,000)
= 143.6 lb/ft³ (÷ 16.018)
= 0.0831 lb/in³
1 m³ of concrete weighs 2.3 tonnes — critical for structural load calculations

Who Uses Density Conversion?

⚙️

Mechanical Engineers

Convert material densities between SI (kg/m³) and US customary (lb/ft³) when using international datasheets and designing components with weight constraints.

🧪

Chemists & Lab Scientists

Use g/cm³ for liquid and solid measurements in lab settings, converting to kg/m³ for SI-compliant reporting or kg/L for solution concentrations.

🏗️

Civil & Structural Engineers

Calculate loads for concrete (2,300 kg/m³), steel (7,850 kg/m³) and soil (1,600–2,000 kg/m³) when designing foundations, slabs and retaining walls.

⛏️

Geologists & Mining Engineers

Determine ore grades and rock densities to estimate tonnage and plan excavation. Convert between g/cm³ (lab measurements) and t/m³ (bulk mining calculations).

🚢

Naval Architects

Calculate buoyancy and ship stability using water density (1,025 kg/m³ sea water vs 1,000 kg/m³ fresh water) and hull material densities.

🎓

Students & Educators

Verify physics and chemistry lab results, cross-check textbook values across unit systems, and understand the relationship between mass, volume and density.

Mental Math Tips

g/cm³ ↔ kg/m³: just move the comma

Multiply or divide by 1,000. Iron = 7.87 g/cm³ → 7,870 kg/m³. Water = 1.00 g/cm³ → 1,000 kg/m³. Since g/cm³ and kg/L are numerically equal, you can also read g/cm³ directly as kg/L.

lb/ft³ ↔ kg/m³: multiply by 16

The exact factor is 16.018, but 16 is close enough for quick estimates. Water ≈ 62.4 lb/ft³ → 62.4 × 16 = 998 kg/m³ (actual: 1,000). Concrete ≈ 150 lb/ft³ → 150 × 16 = 2,400 kg/m³ (actual: 2,300).

Specific gravity = density in g/cm³

Specific gravity (SG) is dimensionless but numerically equals density in g/cm³. Gold SG 19.3 = 19.3 g/cm³. If SG < 1 it floats in water; if SG > 1 it sinks. No conversion needed — just read the g/cm³ value as the SG directly.

Frequently Asked Questions — Density Converter

Density is mass per unit volume: ρ = m/V. It tells you how much mass is packed into a given space. Water has density 1,000 kg/m³ (1 g/cm³). Steel is about 7,850 kg/m³, aluminum 2,700 kg/m³, and gold 19,300 kg/m³. Objects less dense than water (density < 1,000 kg/m³) float; denser objects sink.

The density of water is exactly 1,000 kg/m³ (1.000 g/cm³ or 1 kg/L) at 4°C. It decreases slightly at higher temperatures: at 20°C it is 998.2 kg/m³, and at 100°C it is 958.4 kg/m³. Sea water is slightly denser at about 1,025 kg/m³ due to dissolved salts. The maximum density of pure water occurs at exactly 3.98°C.

The density of dry air at sea level (15°C, 101.325 kPa) is approximately 1.225 kg/m³. This varies with temperature, altitude and humidity — warmer, higher-altitude air is less dense. At 0°C it is approximately 1.293 kg/m³. Hot air balloons work because heated air (lower density) creates buoyancy relative to the surrounding cooler, denser air.

Multiply by 1,000: 1 g/cm³ = 1,000 kg/m³. This is because 1 cm³ = 10⁻⁶ m³ and 1 g = 10⁻³ kg, so the ratio is 10⁻³/10⁻⁶ = 1,000. Example: iron has density 7.87 g/cm³ = 7,870 kg/m³. To convert kg/m³ to g/cm³, divide by 1,000. Use this converter above for instant results in all supported units.

The densest common materials (kg/m³): osmium 22,590, iridium 22,560, platinum 21,450, gold 19,300, tungsten 19,250, lead 11,340, silver 10,500, copper 8,960, iron/steel 7,850, aluminum 2,700, concrete 2,300, water 1,000, wood 400–900, air 1.2. Osmium and iridium are the densest naturally occurring elements.

Multiply by 16.0185: 1 lb/ft³ = 16.0185 kg/m³. This is because 1 pound = 0.4536 kg and 1 cubic foot = 0.02832 m³, giving 0.4536 ÷ 0.02832 = 16.0185. Example: wood at 40 lb/ft³ = 641 kg/m³. To convert kg/m³ to lb/ft³, divide by 16.0185. Water in imperial units is approximately 62.4 lb/ft³.

Specific gravity (SG) is the ratio of a substance's density to the density of water (1,000 kg/m³). It is dimensionless — water has SG = 1, gold SG = 19.3, aluminum SG = 2.7, lead SG = 11.3. Objects with SG < 1 float in water; SG > 1 sink. Specific gravity numerically equals density in g/cm³, making it convenient for quick mental calculations.

All Density Conversions

Common

kg/m³ → g/cm³ g/cm³ → kg/m³ kg/m³ → kg/L kg/L → kg/m³ g/cm³ → kg/L kg/L → g/cm³

Metric

kg/m³ → g/cm³ g/cm³ → kg/m³ kg/m³ → kg/L kg/L → kg/m³

Imperial & US

lb/ft³ → kg/m³ kg/m³ → lb/ft³ lb/in³ → g/cm³ g/cm³ → lb/in³ lb/ft³ → lb/in³ oz/in³ → g/cm³