Volume & weight
Why Cubic Yard Weight Varies
Equal volume does not mean equal weight. The number that links cubic yards to tons is bulk density, and it changes with the material and its condition.
By Kumar Baniya, MEng in Structural Engineering (University of Leeds) · Last reviewed
Density connects volume and weight
Cubic yards measure space. Tons measure weight. To go from one to the other you need the bulk density: the weight of material in a given volume, including the air or water in the gaps between particles.
Weight (lb) = volume (yd³) × bulk density (lb/yd³)
With illustrative densities, 4 yd³ of a material at 1,000 lb/yd³ weighs 2 US short tons, while 4 yd³ at 2,700 lb/yd³ weighs 5.4 tons — the same volume, almost three times the weight. These numbers only show the arithmetic; they are not values for any particular product.
The material itself
Stone, soil and wood are made of substances with very different weights. Organic materials such as bark and compost are light for their volume; crushed rock is heavy. A product name alone does not tell you the density, because suppliers’ products differ.
Particle size and gaps
Bulk material is never solid. Uniform, rounded pieces leave larger gaps between them; a mix of sizes lets small particles fill the gaps between larger ones, packing more material — and more weight — into the same volume.
Moisture
Water is heavy. At 1,000 kg/m³, water weighs about 62.4 lb per cubic foot, or about 1,686 lb per cubic yard. If water filled just 10% of the volume of a cubic yard of material, it would add about 169 lb. That is why the same stockpile can weigh noticeably more after rain.
Loose or compacted
Loose material has more air between particles than the same material after it has been compacted. So a cubic yard of compacted material contains more material, and weighs more, than a loose cubic yard. Always use a density that matches the state of the volume you are converting — usually the loose, as-delivered state when you are ordering.
If your measurement is a finished, compacted depth, ask the supplier for a loose-to-finished factor. A factor of 1.25 means 1 yd³ finished needs 1.25 yd³ loose. Note that a 20% shrinkage is a factor of 1 ÷ 0.8 = 1.25, not 1.20. The gravel calculator applies the factor and your allowance separately so nothing is counted twice.
Which ton?
| Unit | Definition |
|---|---|
| US short ton | 2,000 lb (907.18474 kg) |
| Metric tonne | 1,000 kg (about 2,204.62 lb) |
| Long ton | 2,240 lb — not used by our calculators |
A metric tonne is about 10.2% heavier than a US short ton, so check which one your quote uses.
Getting the right number
- Ask your supplier for the bulk density they use to convert between yards and tons for the exact product.
- Ask whether it applies to loose, as-delivered material.
- If you are buying by weight, the scale ticket shows what was actually delivered.
- Avoid generic tables for ordering; they cannot know your product or its moisture.
Reversing works the same way: tons × 2,000 ÷ density. For example, 10 short tons at an illustrative 2,700 lb/yd³ is 7.41 yd³. The cubic yards to tons calculator does both directions at full precision.