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Density Converter - kg/m³, g/cm³, lb/ft³ & More | Free Online Density Unit Calculator

Instantly convert density between kg/m³, g/cm³, lb/ft³, lb/in³, slug/ft³, t/m³, g/mL, and more. Free online density unit converter for engineering, chemistry, physics, and materials science - accurate to 6 decimal places using NIST-standard conversion factors.

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What Is a Density Converter?

A density converter is a free online calculator that instantly translates mass-per-volume values between all major metric and imperial density units. Density - defined as mass divided by volume (ρ = m/V) - is one of the most fundamental physical properties in science and engineering. Because different industries and countries use different unit systems, the ability to convert kg/m³ to g/cm³, convert lb/ft³ to kg/m³, convert g/cm³ to lb/in³, and switch between any other pair of density units is an everyday requirement for engineers, chemists, physicists, material scientists, and students.

Our free density unit converter supports 15 units across metric (SI), CGS, and imperial/US customary systems. All conversion factors are sourced from the National Institute of Standards and Technology (NIST)and are accurate to 6 decimal places - sufficient for virtually all professional and academic applications.

Conversions update automatically as you type, eliminating the need to press a button for every calculation. Your last-used unit pair and value are saved in your browser for up to 30 days, so your workflow is never interrupted.

How to Use the Density Converter - Step-by-Step

Converting any density value with this online density calculatortakes just seconds:

  1. Type your density value into the left input field. The tool accepts integers, decimals (e.g., 1.225 for air density), and any positive number up to 20 digits.
  2. Select the source unit from the "From Unit" dropdown. For example, choose kg/m³ if your value comes from a scientific paper, or lb/ft³ if it comes from a US engineering spec sheet.
  3. Select the target unit from the "To Unit" dropdown on the right panel. The result appears automatically - no need to click Convert unless you prefer manual control.
  4. Read the result in the output panel, displayed as a 6-decimal value alongside the full conversion equation (e.g., "1000 kg/m³ = 1.000000 g/cm³").
  5. Copy the result with one click using the Copy button, or click Swap Units to instantly reverse the conversion direction.
  6. Click Clear to reset everything and start fresh.

Density Unit Conversion Reference Table

The table below lists exact NIST-standard conversion factors from each unit to kg/m³ - the SI base unit for density. Use this as your density conversion chart for quick manual calculations.

Unit NameSymbol= kg/m³System
Kilogram per Cubic Meterkg/m³1 (base unit)SI / Metric
Gram per Cubic Centimeterg/cm³1,000CGS / Metric
Gram per Milliliterg/mL1,000CGS / Metric
Gram per Literg/L1Metric
Kilogram per Literkg/L1,000Metric
Metric Ton per Cubic Metert/m³1,000Metric
Milligram per Litermg/L0.001Metric
Pound per Cubic Footlb/ft³16.018463Imperial/US
Pound per Cubic Inchlb/in³27,679.905Imperial/US
Ounce per Cubic Inchoz/in³1,729.994Imperial/US
Ounce per Cubic Footoz/ft³1.001154Imperial/US
Pound per US Gallonlb/gal (US)119.826US Customary
Pound per UK Gallonlb/gal (UK)99.776Imperial
Slug per Cubic Footslug/ft³515.379Imperial
Ton per Cubic Yardton/yd³1,328.939Imperial/US

Understanding All Density Units in Depth

Kilograms per Cubic Meter (kg/m³) - The SI Standard

The kilogram per cubic meter (kg/m³) is the official SI base unit of density, defined as the mass in kilograms of a substance occupying one cubic meter of volume. It is the standard unit in scientific literature, international engineering standards, and academic publications worldwide.

Water at 4 °C has a density of exactly 1,000 kg/m³. Air at sea level is approximately 1.225 kg/m³. Steel sits around 7,850 kg/m³. To convert kg/m³ to g/cm³, simply divide by 1,000 (e.g., 1,000 kg/m³ = 1 g/cm³). To convert kg/m³ to lb/ft³, multiply by 0.062428 (e.g., 1,000 kg/m³ = 62.428 lb/ft³).

Grams per Cubic Centimeter (g/cm³) - The Chemistry Standard

The gram per cubic centimeter (g/cm³) is the most common density unit in chemistry and materials science. It is part of the CGS (centimeter–gram–second) system and is numerically equivalent to g/mL and kg/L. The gram was originally defined as the mass of 1 cm³ of water at 4 °C, which is why water's density is so conveniently 1 g/cm³.

This unit is ideal for describing the density of liquids, solids, and materials at laboratory scale. Aluminum is 2.70 g/cm³; copper is 8.96 g/cm³; gold is 19.32 g/cm³. To convert g/cm³ to kg/m³, multiply by 1,000. To convert g/cm³ to lb/ft³, multiply by 62.428.

Pounds per Cubic Foot (lb/ft³) - The US Engineering Standard

The pound per cubic foot (lb/ft³) is the dominant density unit in US construction, structural engineering, HVAC, and civil engineering. One lb/ft³ equals 16.018463 kg/m³. Water's density in these units is approximately 62.43 lb/ft³. Concrete typically ranges from 137–156 lb/ft³; structural steel is about 490 lb/ft³.

To convert lb/ft³ to kg/m³, multiply by 16.018463. To convert lb/ft³ to g/cm³, multiply by 0.016018. This conversion is among the most frequently searched density conversions for engineers working across metric and imperial specifications simultaneously.

Pounds per Cubic Inch (lb/in³) - Metals & High-Density Materials

The pound per cubic inch (lb/in³) is commonly used in mechanical and aerospace engineering when specifying metal alloy densities at the component level. One lb/in³ = 27,679.9 kg/m³. Steel has a density of approximately 0.284 lb/in³; aluminum is about 0.098 lb/in³; titanium is roughly 0.163 lb/in³. To convert lb/in³ to g/cm³, multiply by 27.6799.

Slugs per Cubic Foot (slug/ft³) - Fluid Mechanics

The slug per cubic foot (slug/ft³) is a unit of density used in fluid mechanics and dynamics in the US customary system. Unlike pounds (a unit of force), the slug is a true unit of mass (1 slug = 14.5939 kg). One slug/ft³ = 515.379 kg/m³. Air at sea level is approximately 0.00237 slug/ft³; water is about 1.94 slug/ft³. This unit is especially important in aerodynamics and naval architecture calculations where mass (not weight) must be distinguished clearly.

Metric Tons per Cubic Meter (t/m³) - Bulk Materials

The metric ton per cubic meter (t/m³) is numerically equal to g/cm³ and kg/L, making conversions between them trivial. It is widely used in the mining, quarrying, bulk materials, and construction industries for reporting the density of large volumes of material. Dry sand has a bulk density of roughly 1.6 t/m³; gravel is 1.7 t/m³; reinforced concrete is about 2.5 t/m³.

Density of Common Materials - Reference Values

Use this density of materials table as a quick reference. All values are approximate at room temperature (20 °C / 68 °F) and standard atmospheric pressure.

Metals & Alloys

  • Aluminum: 2,700 kg/m³ | 2.70 g/cm³ | 168.6 lb/ft³
  • Copper: 8,900 kg/m³ | 8.90 g/cm³ | 555.8 lb/ft³
  • Steel (carbon): 7,850 kg/m³ | 7.85 g/cm³ | 490.0 lb/ft³
  • Iron (cast): 7,200 kg/m³ | 7.20 g/cm³ | 449.5 lb/ft³
  • Gold: 19,320 kg/m³ | 19.32 g/cm³ | 1,206 lb/ft³
  • Silver: 10,490 kg/m³ | 10.49 g/cm³ | 655 lb/ft³
  • Lead: 11,340 kg/m³ | 11.34 g/cm³ | 708 lb/ft³
  • Titanium: 4,506 kg/m³ | 4.51 g/cm³ | 281 lb/ft³
  • Brass: 8,500 kg/m³ | 8.50 g/cm³ | 531 lb/ft³

Liquids (at 20 °C)

  • Water (4 °C): 1,000 kg/m³ | 1.00 g/cm³ | 62.4 lb/ft³
  • Seawater: 1,025 kg/m³ | 1.025 g/cm³ | 64.0 lb/ft³
  • Milk: 1,030 kg/m³ | 1.03 g/cm³ | 64.3 lb/ft³
  • Petrol/Gasoline: 730 kg/m³ | 0.73 g/cm³ | 45.6 lb/ft³
  • Diesel fuel: 850 kg/m³ | 0.85 g/cm³ | 53.1 lb/ft³
  • Ethanol: 789 kg/m³ | 0.789 g/cm³ | 49.3 lb/ft³
  • Mercury: 13,534 kg/m³ | 13.53 g/cm³ | 845 lb/ft³
  • Olive oil: 900 kg/m³ | 0.90 g/cm³ | 56.2 lb/ft³

Construction Materials

  • Concrete (normal): 2,400 kg/m³ | 2.40 g/cm³ | 149.8 lb/ft³
  • Brick: 1,900 kg/m³ | 1.90 g/cm³ | 118.6 lb/ft³
  • Granite: 2,650 kg/m³ | 2.65 g/cm³ | 165.4 lb/ft³
  • Sand (dry): 1,600 kg/m³ | 1.60 g/cm³ | 99.9 lb/ft³
  • Gravel: 1,700 kg/m³ | 1.70 g/cm³ | 106.1 lb/ft³
  • Glass: 2,500 kg/m³ | 2.50 g/cm³ | 156.1 lb/ft³
  • Gypsum board: 800 kg/m³ | 0.80 g/cm³ | 49.9 lb/ft³

Wood & Gases

  • Oak (hardwood): 750 kg/m³ | 0.75 g/cm³ | 46.8 lb/ft³
  • Pine (softwood): 550 kg/m³ | 0.55 g/cm³ | 34.3 lb/ft³
  • Balsa: 170 kg/m³ | 0.17 g/cm³ | 10.6 lb/ft³
  • Plywood: 700 kg/m³ | 0.70 g/cm³ | 43.7 lb/ft³
  • Air (sea level): 1.225 kg/m³ | 0.001225 g/cm³ | 0.0765 lb/ft³
  • CO₂: 1.977 kg/m³ | 0.001977 g/cm³
  • Hydrogen: 0.0899 kg/m³| 0.0000899 g/cm³

What Is Density? Definition, Formula & Units Explained

Density is defined as the amount of mass contained in a unit of volume. The formula is:

ρ = m / V

where ρ (rho) is density, m is mass, and V is volume. It quantifies how "compact" or "heavy" a material is per unit of space it occupies.

Density is a critical property across almost every branch of science and engineering:

  • Buoyancy: Objects float in a fluid if their density is less than the fluid's. Ice (917 kg/m³) floats on water (1,000 kg/m³); steel sinks because 7,850 > 1,000.
  • Material selection: Engineers select materials partly based on density - a lighter material (lower density) reduces structural weight in aerospace, automotive, and civil applications.
  • Fluid mechanics: Density determines pressure gradients, buoyancy forces, and flow behavior in pipes and channels.
  • Chemistry & pharmacy: Solution concentration is often expressed as density (e.g., g/mL), and purity can be inferred from density measurements.
  • Geology & mining: Rock and ore densities determine drilling, blasting, and extraction parameters.
  • Food science: Density is used to measure sugar concentration in beverages (Brix scale) and fat content in dairy products.

Density changes with temperature (most materials expand when heated, lowering their density) and pressure (especially gases). The values in this tool's reference table are for room temperature (~20 °C) and standard atmospheric pressure (1 atm).

Most Common Density Conversions & Quick Formulas

kg/m³ Conversions

  • × 0.001 → g/cm³
  • × 0.001 → g/mL
  • × 0.001 → kg/L
  • × 0.062428 → lb/ft³
  • × 0.000036127 → lb/in³
  • × 0.008345 → lb/gal (US)
  • × 0.0007525 → ton/yd³
  • × 0.001940 → slug/ft³

g/cm³ Conversions

  • × 1000 → kg/m³
  • × 1 → g/mL
  • × 1 → kg/L
  • × 62.428 → lb/ft³
  • × 0.036127 → lb/in³
  • × 1.7280 → oz/in³
  • × 1000 → t/m³

lb/ft³ Conversions

  • × 16.01846 → kg/m³
  • × 0.016018 → g/cm³
  • × 0.000578704 → lb/in³
  • × 0.009259 → oz/in³
  • × 16.01846 → g/L
  • × 0.133681 → lb/gal (US)
  • × 0.01205 → ton/yd³

Specific Gravity Relationship

Specific gravity (SG) is a dimensionless ratio of a material's density to the density of water at 4 °C (1,000 kg/m³ or 1 g/cm³). It is numerically equal to density in g/cm³ for liquids and solids. For example, a material with SG = 2.5 has a density of 2.5 g/cm³ = 2,500 kg/m³ = 156.1 lb/ft³. To convert specific gravity to kg/m³, simply multiply by 1,000.

Who Uses a Density Converter & Why

Civil & Structural Engineers

Specifying loads, mix designs, and material takeoffs requires switching between kg/m³ (international standards) and lb/ft³ (US codes like ACI and ASCE). This tool converts instantly, reducing transcription errors in structural calculations.

Mechanical & Aerospace Engineers

Metal alloy data sheets list densities in lb/in³ (US) or g/cm³ (metric). Weight budget calculations and finite-element models need consistent units. Converting aluminum's 0.098 lb/in³ to 2,712 kg/m³ is one click away.

Chemists & Lab Scientists

Solution densities, reagent purity checks, and concentration calculations all involve g/mL or g/cm³. Converting to SI units (kg/m³) for publication or comparing with materials databases is a routine task this tool handles instantly.

Geologists & Mining Engineers

Rock, ore, and soil densities are measured in g/cm³ in the laboratory and reported in t/m³ for bulk volume estimates. Understanding when 2.65 g/cm³ granite becomes 2.65 t/m³ - or 165 lb/ft³ - matters for geotechnical design.

Students & Educators

Physics and chemistry students regularly need to convert density units for homework, lab reports, and exams. This tool provides instant, verifiable answers and serves as a learning aid for understanding the relationships between unit systems.

HVAC & Fluid Systems Engineers

Air, refrigerant, and fluid densities in slug/ft³ or lb/ft³ must often be reconciled with SI-unit simulation software. This converter handles slug/ft³ conversions that many other tools overlook.

Frequently Asked Questions (FAQ)

How do I convert kg/m³ to g/cm³?

To convert kg/m³ to g/cm³, divide by 1,000. For example, water's density of 1,000 kg/m³ equals 1 g/cm³. This is because 1 m³ = 1,000,000 cm³ and 1 kg = 1,000 g, so the ratio simplifies to ÷1,000. Conversely, to convert g/cm³ to kg/m³, multiply by 1,000.

How do I convert lb/ft³ to kg/m³?

To convert lb/ft³ to kg/m³, multiply by 16.018463. For example, concrete at 150 lb/ft³ × 16.018463 = 2,402.8 kg/m³. To go the other way (kg/m³ to lb/ft³), multiply by 0.062428.

What is the density of water in all units?

Water at 4 °C (its maximum density): 1,000 kg/m³ = 1 g/cm³ = 1 g/mL = 1 kg/L = 1 t/m³ = 62.428 lb/ft³ = 0.036127 lb/in³ = 0.5780 oz/in³ = 1.9403 slug/ft³ = 8.345 lb/gal (US) = 10.022 lb/gal (UK).

What is the difference between density and specific gravity?

Density has units (kg/m³, g/cm³, etc.) and represents the mass per unit volume of a substance. Specific gravity (SG) is a dimensionless number - the ratio of a material's density to the density of water at 4 °C. Numerically, SG equals density in g/cm³ for solids and liquids. For example, aluminum has SG = 2.70, meaning it is 2.70 times denser than water. To convert SG to kg/m³, multiply by 1,000.

Are g/cm³, g/mL, and kg/L the same?

Yes - g/cm³, g/mL, and kg/L are numerically identical. This is because 1 cm³ = 1 mL and 1 L = 1,000 mL = 1,000 cm³, so 1 g/cm³ = 1 g/mL = 1 kg/L. They are different unit expressions of the same quantity and can be used interchangeably in all calculations.

What is a slug per cubic foot (slug/ft³)?

A slug is the unit of mass in the US customary engineering system (as opposed to pounds, which are a unit of force). One slug equals 14.5939 kg. Therefore, 1 slug/ft³ = 515.379 kg/m³. This unit appears mainly in fluid mechanics and aerodynamics textbooks. Water is approximately 1.9403 slug/ft³; air at sea level is about 0.002377 slug/ft³.

How accurate are the conversions?

All conversion factors in this tool are sourced from NIST (National Institute of Standards and Technology)and the CRC Handbook of Chemistry and Physics. Results are displayed to 6 decimal places. All calculations run locally in your browser using JavaScript double-precision (64-bit) floating-point arithmetic, which provides approximately 15–16 significant digits of precision.

Is my data secure? Does this tool store my values?

All calculations happen entirely in your browser - no data is sent to any server. Your input value and unit selection are saved only in your browser's own localStorage (on your device) for convenience, and are automatically cleared after 30 days. You can manually clear them at any time using the Clear button.

Can I use this tool offline?

Yes. Once the page has fully loaded in your browser, the density converter works completely offline. No internet connection is required for calculations, as all conversion logic is embedded in the page itself.

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