Loose bulk densities for 18 common bulk materials in lb/yd³, tons/yd³, and kg/m³, plus typical angles of repose. Bulk density is the weight of material per unit volume as it sits in a pile, voids included, and it's the number that turns a measured volume into tonnage.
| Material | lb/yd³ (loose) | tons/yd³ | kg/m³ | Angle of repose |
|---|---|---|---|---|
| Gravel | 2,800 | 1.40 | 1,661 | ~34° |
| Pea gravel | 2,600 | 1.30 | 1,543 | ~30° |
| Crushed stone | 2,700 | 1.35 | 1,602 | ~37° |
| Limestone (crushed) | 2,600 | 1.30 | 1,543 | ~38° |
| Sand (dry) | 2,700 | 1.35 | 1,602 | ~34° |
| Sand (wet) | 3,200 | 1.60 | 1,899 | ~25° |
| Topsoil | 2,000 | 1.00 | 1,187 | ~35° |
| Fill dirt | 2,200 | 1.10 | 1,305 | ~35° |
| Asphalt millings | 2,400 | 1.20 | 1,424 | ~35° |
| Concrete (crushed) | 2,400 | 1.20 | 1,424 | ~37° |
| Road salt | 2,000 | 1.00 | 1,187 | ~32° |
| Coal (bituminous) | 1,500 | 0.75 | 890 | ~35° |
| Corn (shelled) | 1,215 | 0.61 | 721 | ~23° |
| Wheat | 1,300 | 0.65 | 771 | ~27° |
| Soybeans | 1,250 | 0.63 | 742 | ~26° |
| Wood chips | 550 | 0.28 | 326 | ~45° |
| Mulch | 700 | 0.35 | 415 | ~40° |
| Compost | 1,000 | 0.50 | 593 | ~40° |
tonnage = volume (yd³) × density (lb/yd³) ÷ 2,000 · kg/m³ = lb/yd³ × 0.5933
Every inventory conversion between volume and weight runs through bulk density, which is why the same 1,000 yd³ pile can be 1,400 tons of gravel or 275 tons of wood chips. Values here are loose, uncompacted planning figures: moisture, gradation, and compaction can move them 20% or more, so use your own scale-ticket densities when precision matters. To run the conversion directly, use the cubic yards to tons calculator, or start from pile dimensions with the stockpile volume calculator.
The angle of repose is the steepest slope a loose material naturally holds. It sets the shape of freestanding piles (and therefore their volume for a given footprint), sizes hopper and chute walls, and explains why wood chips stack tall and narrow while wet sand slumps wide. Most aggregates and grains fall between 25° and 40°.
Bulk density is the mass of a granular material per unit of volume as it actually sits, including the air between particles. It's always lower than the solid particle density: crushed limestone rock is ~2,600 kg/m³ solid, but a loose pile of it runs ~1,550 kg/m³ because roughly 40% of the pile is void space.
Loose bulk density describes freshly dumped, uncompacted material; compacted (or tapped) density describes the same material after vibration, traffic, or settling, and typically runs 10–25% higher. Inventory measurements of stockpiles should use loose density unless the pile is old and trafficked.
Multiply lb/yd³ by 0.5933 to get kg/m³, or multiply kg/m³ by 1.686 to get lb/yd³. To get US tons per cubic yard, divide lb/yd³ by 2,000.
Moisture is the usual culprit: wet sand weighs roughly 20% more than dry. Gradation, compaction, and material source move values too. Chart densities are planning figures; scale tickets from your own material are the ground truth, and Rebulk uses your ticket-derived densities when converting measured volumes to tonnage.
Rebulk converts measured volume through your real, ticket-derived densities instead of chart averages, and goes a level deeper with packing-factor and void-fraction analysis: how much of the pile is material and how much is air. For irregular materials like logs, chips, and baled biomass, that's the difference between a number and the truth.
