Density Converter: kg/m³, g/cm³, lb/ft³ & More

Convert density between kg/m³, g/cm³, lb/ft³, g/L, lb/gal, and 40+ units. Whether you need kg/m³ to g/cm³, pound per cubic foot to kg/m³, or any SI, imperial, or specialty unit (slug/ft³, psi/1000 ft), this converter uses the SI base (kilogram per cubic meter) for accurate results. Free, runs in your browser—no sign-up required.

What is density?

Density is mass per unit volume—how much mass is packed into a given space. Its dimension is mass/length³. The SI unit is kilogram per cubic meter (kg/m³). In chemistry and materials you’ll see g/cm³ (water ≈ 1), in US engineering lb/ft³ and lb/gal, and in specialty contexts slug/ft³, psi/1000 ft, or Earth’s mean density. This converter supports 40+ units. Every value is normalized to kg/m³ under the hood.

How density conversion works

Density is mass per unit volume. Convert your value into kg/m³ using the source unit’s factor, then divide by the target unit’s factor:

\text{Result} = \text{Value} \times \frac{\text{source (kg/m}^3\text{)}}{\text{target (kg/m}^3\text{)}}

Example: 1 g/cm³ to kg/m³ → 1 × 1000 ÷ 1 = 1000 kg/m³. Water at 4°C is about 1000 kg/m³ (1 g/cm³). The converter supports metric (kg/m³, g/L, mg/L), imperial (lb/ft³, lb/gal), and specialty units (slug/ft³, psi/1000 ft, Earth’s mean density).

Key Density Units Explained

Each unit’s factor to kg/m³ — what this density converter uses. Mass-per-volume units can be written as mass/length³ (e.g. kg/m³) or mass/liter (e.g. g/L); 1 kg/L = 1000 kg/m³.

Kilogram/cubic meter (kg/m³)

Factor: 1 (SI base unit)

The SI derived unit for density. Used in physics, engineering, and fluid mechanics. Water at 4°C ≈ 1000 kg/m³; air at sea level ≈ 1.225 kg/m³.

Gram/cubic centimeter (g/cm³)

Factor: $1\,\text{g/cm}^3 = 1000\,\text{kg/m}^3$

Common in chemistry and materials. Water ≈ 1 g/cm³. Metals: iron ~7.87, lead ~11.3, gold ~19.3 g/cm³.

Gram/liter (g/L)

Factor: 1 g/L = 1 kg/m³

Same numerical value as kg/m³. Used for solutions (e.g. concentration as mass per liter).

Pound/cubic foot (lb/ft³)

Factor: 1 lb/ft³ ≈ 16.018 kg/m³

Common in US engineering, construction, and HVAC. Water ≈ 62.43 lb/ft³. Often used for bulk materials and fluids.

Pound/gallon (US)

Factor: 1 lb/gal (US) ≈ 119.83 kg/m³

Used for liquids in the US (fuel, chemicals). Water ≈ 8.34 lb/gal (US). UK gallon is larger, so lb/gal (UK) has a different factor.

Slug/cubic foot

Factor: 1 slug/ft³ ≈ 515.4 kg/m³

Slug is mass in the imperial technical system (1 slug = 32.174 lb). Used in US fluid dynamics and aerospace.

Earth's density (mean)

Factor: ~5514 kg/m³

Mean density of Earth (mass/volume). Used in geophysics and astronomy. Earth’s interior is much denser than surface rock.

Psi/1000 feet

Factor: ~2.31 kg/m³ per psi/1000 ft

Pressure gradient expressed as equivalent fluid density. Used in drilling and wellbore hydraulics (e.g. mud weight).

When to use kg/m³ vs g/cm³ vs lb/ft³

kg/m³ is the SI unit and is preferred in physics and fluid mechanics (e.g. ρ in P = ρgh). g/cm³ is common in chemistry and materials—water at 4°C ≈ 1 g/cm³; metals are often in g/cm³. g/L has the same numerical value as kg/m³ and is used for solutions. lb/ft³ and lb/gal appear in US engineering, construction, and HVAC. Slug/ft³ is used in US fluid dynamics. This converter supports all of these so you can match datasheets and formulas.

Who uses a density converter?

Chemists and materials scientists convert between g/cm³ and kg/m³ for papers and specs. Mechanical and HVAC engineers work with lb/ft³ or lb/gal for fluids and bulk materials. Students and educators use it to check homework (e.g. “convert 1000 kg/m³ to g/cm³”) and to relate ρ = m/V to real-world units. Water at 4°C ≈ 1000 kg/m³ (1 g/cm³); air at sea level ≈ 1.2 kg/m³. All conversions run in your browser—no data is sent to a server.

Common density conversions at a glance

Handy reference for kg/m³ to g/cm³, lb/ft³ to kg/m³, and other everyday density conversions.

From	To	Formula	Example
kg/m³	g/cm³	÷ 1000	1000 kg/m³ = 1 g/cm³
g/cm³	kg/m³	× 1000	1 g/cm³ = 1000 kg/m³
lb/ft³	kg/m³	× 16.018	62.43 lb/ft³ ≈ 1000 kg/m³
kg/m³	lb/ft³	÷ 16.018	1000 kg/m³ ≈ 62.43 lb/ft³
g/L	kg/m³	× 1	1 g/L = 1 kg/m³
lb/gal (US)	kg/m³	× 119.83	8.34 lb/gal ≈ 1000 kg/m³

Why kilogram per cubic meter is the SI unit

Density is mass divided by volume. The SI base units are kilogram (mass) and meter (length), so density in SI is kg/m³. Gram per cubic centimeter (g/cm³) and gram per liter (g/L) are common in chemistry and give the same scale as water ≈ 1. Imperial and US customary units (lb/ft³, lb/gal) use pound and gallon; the converter uses fixed conversion factors so every result is consistent.

Avoiding common mistakes

Don’t confuse density (mass/volume, e.g. kg/m³) with specific volume (volume/mass, e.g. m³/kg)—they’re reciprocals. Don’t mix lb/gal (US) and lb/gal (UK) without converting; the UK gallon is larger. g/L and kg/m³ are numerically equal (1 g/L = 1 kg/m³), but always confirm the unit. When in doubt, convert everything to kg/m³ with this tool, then apply your formulas (e.g. ρ in P = ρgh).

Density Conversion FAQ

? How do I convert kg/m³ to g/cm³?

Divide by 1000. 1 kg/m³ = 0.001 g/cm³, so 1000 kg/m³ = 1 g/cm³ (water at 4°C). To convert g/cm³ to kg/m³, multiply by 1000.

? How do you convert pound per cubic foot to kg/m³?

Multiply lb/ft³ by about 16.018 to get kg/m³. For example, 62.43 lb/ft³ ≈ 1000 kg/m³ (water). To convert kg/m³ to lb/ft³, divide by 16.018.

? What is the SI unit of density?

Kilogram per cubic meter (kg/m³). It’s derived from SI base units: mass (kg) and length (m). Gram per cubic centimeter (g/cm³) and gram per liter (g/L) are accepted in use with SI and are numerically convenient (water ≈ 1).

? When is psi/1000 feet used?

Psi per 1000 feet is a pressure gradient used in drilling and wellbore fluid (mud) weight. It can be expressed as an equivalent fluid density (~2.31 kg/m³ per psi/1000 ft). This converter includes it for oil & gas and geotechnical work.

? Is g/cm³ the same as g/mL?

Yes. 1 cm³ = 1 mL, so 1 g/cm³ = 1 g/mL. Both equal 1000 kg/m³. Chemistry often uses g/mL for liquid density. This converter uses g/cm³; the numerical value is the same as g/mL.

? What is the density of water in lb/ft³?

Water at 4°C is about 62.43 lb/ft³ (1000 kg/m³). To convert 1000 kg/m³ to lb/ft³, multiply by 0.06243 (or divide 1000 by 16.018). Sea water is slightly denser (~64 lb/ft³). This converter supports lb/ft³ so you can switch between metric and imperial.

Density Conversion Tool