Asphalt Density Calculator: Free Online Density Converter
Use our free asphalt density calculator to convert between pounds per cubic foot (lb/ft³), kilograms per cubic meter (kg/m³), and tons per cubic yard (tons/cu yd). Designed for contractors, mix designers, and quality control technicians, this tool helps you switch between density units instantly and verify compaction specifications. Reference density values for common asphalt types are included below.
How to use this calculator.
- Select your input unit. Choose the density unit you currently have: lb/ft³, kg/m³, or tons/cu yd.
- Enter the density value. Input the known density of your asphalt mix. If you are unsure, use the reference values provided below for common mix types.
- View all conversions. The calculator instantly displays the equivalent density in all three units: imperial, metric, and construction-yard.
- Compare with reference values. Check your result against the standard density ranges for hot mix, warm mix, and cold mix asphalt to verify your mix design is within specification.
- Print or save. Use your browser's print function to keep a record of your density conversions for QC documentation.
How do you calculate asphalt density conversions and values?
Asphalt density is the mass per unit volume of compacted asphalt mix. Converting between density units requires multiplying by the appropriate conversion factor.
lb/ft³ to kg/m³: Multiply by 16.0185
kg/m³ to lb/ft³: Divide by 16.0185
lb/ft³ to tons/cu yd: Multiply by 0.0135
tons/cu yd to lb/ft³: Divide by 0.0135
kg/m³ to tons/cu yd: Multiply by 0.0008428
Where:
- lb/ft³ (pounds per cubic foot): The standard imperial unit for asphalt density used in US construction specifications.
- kg/m³ (kilograms per cubic meter): The standard metric (SI) unit for density used internationally.
- tons/cu yd (tons per cubic yard): A practical construction unit used to estimate truck loads and material orders.
Reference Asphalt Density Values
Standard densities for common asphalt mix types at full compaction:
- Hot Mix Asphalt (HMA): Dense Grade: 140–150 lb/ft³ (2,240–2,400 kg/m³). Typical design value: 145 lb/ft³ (2,322 kg/m³).
- Warm Mix Asphalt (WMA): 138–148 lb/ft³ (2,210–2,370 kg/m³). Slightly lower due to reduced compaction temperature.
- Stone Matrix Asphalt (SMA): 145–155 lb/ft³ (2,320–2,480 kg/m³). Higher stone content increases density.
- Cold Mix Asphalt: 125–140 lb/ft³ (2,000–2,240 kg/m³). Lower density due to air voids and solvent content.
- Porous Asphalt / Open Grade: 120–135 lb/ft³ (1,920–2,160 kg/m³). High air void content reduces density significantly.
- Milled RAP (Reclaimed Asphalt Pavement): 115–130 lb/ft³ (1,840–2,080 kg/m³) in loose state. Compacted RAP approaches HMA density.
Example calculation.
Let's convert the density of a standard hot mix asphalt design.
Scenario: A mix design specifies a target density of 2,350 kg/m³. You need this value in lb/ft³ and tons/cu yd for your paving crew.
- Convert to lb/ft³: 2,350 kg/m³ ÷ 16.0185 = 146.7 lb/ft³
- Convert to tons/cu yd: 146.7 lb/ft³ × 0.0135 = 1.98 tons/cu yd
Result: A density of 2,350 kg/m³ equals approximately146.7 lb/ft³ or 1.98 tons/cu yd. This is within the typical range for dense-grade hot mix asphalt.
Reverse check: Starting from 1.98 tons/cu yd, divide by 0.0135 to get 146.7 lb/ft³, then multiply by 16.0185 to get 2,350 kg/m³. All values are consistent.
Tips from the field.
- Always verify with a nuclear density gauge. Theoretical maximum density (Rice test) and in-place density readings should agree within 2–3% for proper compaction.
- Air voids matter. Standard HMA is designed for 3–5% air voids at compaction. If your field density is too low, you have excess air voids and reduced pavement life.
- Temperature changes density readings. Nuclear gauges require temperature correction. Cold pavement reads artificially high; always apply the manufacturer's correction factor.
- Loose mix density is much lower. Freshly placed, uncompacted HMA is roughly 80–85% of its compacted density. Do not use loose density for yield calculations.
- Specific gravity is not density. Bulk specific gravity (Gmb) is dimensionless. Multiply by 62.4 lb/ft³ (density of water) to get density in lb/ft³.
Disclaimer: This calculator provides estimates for planning purposes only. Actual material requirements vary based on site conditions, mix design, compaction, and waste. For structural designs or load-bearing applications, consult a licensed civil engineer. PavementCalculator.com assumes no liability for material overages or shortages.
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.
What is the density of asphalt?
Standard hot mix asphalt (HMA) has a compacted density of 145 lb/ft³ (2,322 kg/m³). Warm mix asphalt (WMA) is approximately 140 lb/ft³ (2,243 kg/m³). Cold mix asphalt is approximately 135 lb/ft³ (2,162 kg/m³). Porous/permeable asphalt is lighter at approximately 120 lb/ft³ (1,922 kg/m³). These are compacted densities: loose asphalt is significantly less dense before compaction.
How do you convert asphalt density from lb/ft³ to kg/m³?
Multiply lb/ft³ by 16.018 to get kg/m³. For example: 145 lb/ft³ × 16.018 = 2,322 kg/m³. Conversely, divide kg/m³ by 16.018 to get lb/ft³. Use our calculator above to convert any asphalt density value between units.
How many tons per cubic yard is asphalt?
At the standard density of 145 lb/ft³: 1 cubic yard of asphalt = 145 lb/ft³ × 27 ft³/yd³ = 3,915 lbs = 1.96 tons. For quick estimation, use 2 tons per cubic yard. One ton of asphalt covers approximately 80-100 sq ft at 2 inches thick or 40-50 sq ft at 4 inches thick. The exact value depends on the specific mix density.
What affects asphalt density?
Asphalt density is affected by: (1) Aggregate type and gradation: heavier aggregates produce denser mixes. (2) Asphalt binder content: higher binder content increases density slightly. (3) Compaction effort: better compaction = higher density. (4) Air voids: design air voids of 3-5% are standard; higher voids = lower density. (5) Temperature: density is measured at ambient temperature; hot asphalt is less dense. (6) Mix type: stone matrix asphalt (SMA) is denser than conventional mixes.
What is the specific gravity of asphalt?
The specific gravity of compacted asphalt typically ranges from 2.2 to 2.5 (dimensionless, relative to water at 4°C). The maximum theoretical specific gravity (Gmm, Rice specific gravity) is typically 2.4-2.6. The bulk specific gravity (Gmb) of compacted specimens is typically 2.2-2.4. Air voids are calculated as: %Air Voids = (1 - Gmb/Gmm) × 100. Target air voids for pavement are typically 4% after construction, settling to 3% under traffic.
How does asphalt density affect tonnage calculations?
Asphalt density directly determines how many tons you need. A 5 lb/ft³ difference in density changes tonnage by approximately 3.5%. For a 1,000 sq ft area at 4 inches thick: at 140 lb/ft³ you need 23.4 tons; at 145 lb/ft³ you need 24.2 tons; at 150 lb/ft³ you need 25.1 tons. Always confirm the density with your asphalt supplier: using the wrong density leads to ordering too much or too little material.
What is the standard density of asphalt?
Standard hot mix asphalt has a compacted density of approximately 145 lb/ft³ (2,322 kg/m³) or 1.96 tons/cu yd. This value varies by mix design, aggregate type, asphalt binder content, and compaction effort. Always confirm with your mix design documentation.
How do I convert asphalt density from kg/m³ to lb/ft³?
Divide the kg/m³ value by 16.0185. For example, 2,350 kg/m³ divided by 16.0185 equals 146.7 lb/ft³. Use our calculator above for instant conversions between any density units.
Why does my compacted density differ from the mix design density?
Several factors reduce in-place density: insufficient compaction effort (roller passes), mix temperature dropping below cessation temperature (typically 175°F), aggregate segregation, or moisture in the underlying layer. Core samples should achieve 92–96% of the theoretical maximum density.
What density should I use for tonnage calculations?
Use the compacted in-place density from your mix design, typically 145 lb/ft³ (1.96 tons/cu yd) for standard HMA. Using a lower density for estimating will result in ordering too little material and a potential cold joint.
Does recycled asphalt (RAP) have different density?
Yes. Loose, unprocessed RAP has a density of about 115–130 lb/ft³. However, once RAP is incorporated into a new HMA mix (typically 15–25% RAP content), the compacted density is nearly identical to virgin HMA. High-RAP mixes (over 25%) may have slightly lower density and require additional compaction effort.