Estimating gravel and aggregate
The volume you need is simply the area times the depth. Suppliers usually sell by weight, so multiply the volume by the material's density to get tonnes. Density varies with the material and how wet it is — dry gravel is around 1.5–1.7 tonnes per cubic metre, sand a little more, so adjust the density if your supplier gives a figure.
Frequently asked questions
What depth should I use?
For a driveway or path, 50 mm for a top layer and up to 100–150 mm for a full base is common. Check your project's requirement.
What density is right?
Dry gravel is about 1.6 t/m³, sand about 1.6–1.8, crushed stone around 1.5. Use the supplier's figure if you have one.
Should I order extra?
Yes — a 5–10% margin covers compaction and uneven ground.