Density Calculator: Free Online Density Converter
Use our free density calculator to convert material densities between all common units. Convert pounds per cubic foot (lb/ft³), kilograms per cubic meter (kg/m³), tons per cubic yard, and more. Essential for construction material estimation when you need to convert between weight and volume for asphalt, concrete, gravel, soil, and other bulk materials.
How to use this calculator.
- Select your source unit. Choose the density unit you currently have: pounds per cubic foot (lb/ft³), kilograms per cubic meter (kg/m³), grams per cubic centimeter (g/cm³), or tons per cubic yard (ton/yd³).
- Enter the density value. Type the material density you want to convert.
- Read all four results at once. The calculator doesn't ask for a single "target" unit: it converts your entry into all four common density units simultaneously.
- Cross-check against reference densities. Compare the converted number to the typical values below to catch a data-entry mistake before it turns into an ordering error.
How do you calculate density unit conversions?
Every conversion routes through pounds per cubic foot (lb/ft³) as a common baseline. Your entered value is first converted to lb/ft³ using a factor that depends on the source unit you selected, then that baseline figure is converted outward into the other three units.
Density (lb/ft³) = Entered Value × Conversion Factor
Density (kg/m³) = Density (lb/ft³) × 16.0185
Density (g/cm³) = Density (lb/ft³) ÷ 62.428
Density (tons/cu yd) = Density (lb/ft³) × 27 ÷ 2,000
Where:
- Entered Value: The density number you type in, in whatever unit you selected.
- Conversion Factor: Set automatically by your source unit selection: 1 for lb/ft³ itself, 0.062428 for kg/m³, 62.428 for g/cm³, and 74.074 for tons/cu yd.
- 16.0185: The number of kg/m³ in one lb/ft³.
- 62.428: The number of lb/ft³ in one g/cm³ (also the density of water in lb/ft³, near enough for construction use).
- 27 ÷ 2,000: Converts a per-cubic-foot weight to a per-cubic-yard weight (× 27) and pounds to short tons (÷ 2,000).
Common reference densities:
- Hot mix asphalt: 145 lb/ft³ (2,322 kg/m³)
- Concrete: 150 lb/ft³ (2,402 kg/m³)
- Gravel (dry): 105 lb/ft³ (1,682 kg/m³)
- Topsoil: 95 lb/ft³ (1,522 kg/m³)
- Water: 62.4 lb/ft³ (1,000 kg/m³)
- 1 ton/cu yd: ≈74.07 lb/ft³ (≈1,186.6 kg/m³)
Example calculation.
Convert a crushed stone density given in metric units into the other three formats.
Scenario: An import spec lists compacted crushed stone at 2,000 kg/m³. Your estimate needs it in lb/ft³, g/cm³, and tons/cu yd.
- Convert to the lb/ft³ baseline: 2,000 kg/m³ × 0.062428 = 124.86 lb/ft³
- Convert to g/cm³: 124.86 lb/ft³ ÷ 62.428 = 2.00 g/cm³
- Convert to tons/cu yd: (124.86 lb/ft³ × 27) ÷ 2,000 = 1.69 tons/cu yd
Result: 2,000 kg/m³ equals approximately124.86 lb/ft³, 2.00 g/cm³, and1.69 tons/cu yd.
Tips from the field.
- Water density is the universal reference. At 4°C, water density is exactly 1,000 kg/m³, 62.4 lb/ft³, and 1 g/cm³. This makes it the baseline for specific gravity calculations across all engineering disciplines.
- Loose vs. compacted density differ significantly.A material's bulk density in a stockpile can be 20–30% lower than its compacted in-place density. Always use the correct density for your application stage.
- Construction density conversions prevent costly errors.Most US construction references use lb/ft³, but international specs use kg/m³. Converting accurately between these avoids material quantity mistakes on international projects.
- g/cm³ and metric tonnes per cubic meter are numerically identical. A material at 2.4 g/cm³ also weighs 2.4 metric tonnes per cubic meter. This shortcut is handy when a lab report gives specific gravity but your estimate needs tonnage.
- Always label your density units on takeoff sheets.A bare number like "145" is meaningless without lb/ft³, kg/m³, or another unit attached. Mislabeled density is one of the most common sources of material over- or under-ordering.
Disclaimer: Density values provided are typical industry averages and vary by region, material source, and moisture conditions. Always confirm actual density with your material supplier. PavementCalculator.com assumes no liability for estimation errors.
Cost, price, and density figures on this page reflect approximate U.S. averages as of August 2026 and vary by region, supplier, and material availability.
Frequently asked questions.
How do you convert lb/ft³ to kg/m³?
Multiply lb/ft³ by 16.0185 to get kg/m³. For example, concrete at 145 lb/ft³ equals approximately 2,323 kg/m³. Our density calculator above handles this conversion instantly.
What is the density of common construction materials?
Common material densities include: concrete 145 lb/ft³ (2,323 kg/m³), asphalt 145 lb/ft³ (2,323 kg/m³), gravel 100 lb/ft³ (1,602 kg/m³), sand 100 lb/ft³ (1,602 kg/m³), topsoil 85 lb/ft³ (1,362 kg/m³), water 62.4 lb/ft³ (1,000 kg/m³), and steel 490 lb/ft³ (7,850 kg/m³).
What is the difference between density and specific gravity?
Density is the mass per unit volume of a substance (e.g., lb/ft³ or kg/m³). Specific gravity is a dimensionless ratio comparing a substance's density to the density of water at 4°C (62.4 lb/ft³ or 1,000 kg/m³). A material with specific gravity of 2.0 is twice as dense as water.
How do you convert g/cm³ to lb/ft³?
Multiply g/cm³ by 62.428 to get lb/ft³. For example, 1 g/cm³ (the density of water) equals 62.428 lb/ft³. Conversely, divide lb/ft³ by 62.428 to get g/cm³.
What is density in construction?
Density is the mass per unit volume of a material, typically measured in lb/ft³ or kg/m³. Standard concrete density is 145-150 lb/ft³. Knowing density is essential for converting between volume (cubic yards) and weight (tons) when ordering bulk materials.
Why does density matter for construction estimating?
Density is the bridge between volume and weight. Most bulk materials are sold by weight (tons), but project dimensions give you volume (cubic yards). You must know the material density to convert accurately and avoid ordering too much or too little material.
What is specific gravity?
Specific gravity (SG) is the ratio of a material's density to the density of water at 4°C. It is dimensionless. An SG of 2.65 means the material is 2.65 times denser than water, or 2,650 kg/m³. It is commonly used in aggregate and soil classification.
How do I convert between lb/ft³ and tons per cubic yard?
Multiply lb/ft³ by 0.0135 to get tons per cubic yard. For example, 145 lb/ft³ × 0.0135 = 1.96 tons/cu yd. Our calculator handles this conversion automatically for all density unit pairs.