Asphalt Density Guide: lb/ft³, kg/m³, and Mix Assumptions
Density is the number most likely to make your tonnage estimate wrong. Here's what it means, what typical values look like, and how to convert between units.
Why density matters
Your tonnage is volume × density. A 5% error in density is a 5% error in tons — on a 20-ton order that's a whole extra ton, or a truck that shows up short. Density is worth one phone call to your plant.
Compacted density, not loose density
The number you need is the compacted density — the weight of the asphalt after it has been rolled in place. Loose mix straight from the truck is lighter (more air voids). Hot mix is sold by actual scale weight; compacted density lets the calculator convert the finished pavement volume into an estimated order weight.
Common compacted densities
| Mix type | lb/ft³ | kg/m³ | Notes |
|---|---|---|---|
| Dense-graded HMA (standard) | 145 | 2,323 | Default planning value; ~109 LB/(SY·IN) |
| Fine-graded / polymer-modified | 150 | 2,403 | Upper end of typical range |
| Open-graded friction course | 135 | 2,163 | Lighter due to deliberate air voids |
| Typical planning range | 100–170 | 1,602–2,723 | Outside this, suspect a unit mix-up |
These are planning assumptions, not engineering specifications. Your plant's mix design gives the real number — ask for it, especially on large orders.
Converting lb/ft³ to kg/m³
Multiply by 16.018:
kg/m³ = lb/ft³ × 16.018 | 145 lb/ft³ × 16.018 ≈ 2,323 kg/m³ |
lb/ft³ = kg/m³ ÷ 16.018 | 2,400 kg/m³ ÷ 16.018 ≈ 149.8 lb/ft³ |
Our calculators do all arithmetic in metric internally and only convert at the edges, so the US and Metric views agree to within display rounding.
Where 110 LB/(SY·IN) comes from
Many US specs quote density as pounds per square yard perinch. One square yard-inch is 9 ft² × (1/12) ft = 0.75 ft³. So:
110 lb ÷ 0.75 ft³ = 146.67 lb/ft³ | the two notations are the same density |
If a supplier says "110 pounds per yard-inch," you can use 146.7 lb/ft³ in any calculator that asks for cubic-foot density.
How to use this in the calculators
The asphalt calculator offers the three presets above plus a custom density field, and warns you if a value falls outside the typical 100–170 lb/ft³ range. For the formulas these densities feed into, see the methodology.