Gravel needed
Volume = length × width × depth · Weight = volume × density
Gravel weighs roughly 1.5 tonnes per m³ (~1.4 tons/yd³). Aim for a 100 mm (4 in) depth on driveways and 50 mm (2 in) on decorative beds. Landscape fabric underneath stops weeds and keeps the stone from sinking.
Estimating gravel for a project
Gravel is sold by the cubic yard or ton. Enter length, width and depth in any units; the calculator converts, computes cubic yards, and multiplies by ~1.4 tons per yard. A typical driveway uses 4–6 inches of depth.
Order a little extra for spreading and compaction.