Free Gravel Quantity calculator with clear step-by-step results.
Gravel is priced by the tonne but specified by depth, so the take-off runs area × depth to get a volume and then multiplies by bulk density to get mass. Typical decorative and drainage gravels sit near 1.6 t/m³ loose. The compaction allowance matters: gravel delivered loose loses volume when it is raked and rolled, so ordering only the finished volume leaves the surface short.
Volume
Volume = area × depth ÷ 1000, then × (1 + compaction allowance)
Mass
Tonnes = order volume × bulk density
Quantities are planning estimates. Confirm bulk density and coverage with your supplier, and follow the drainage and sub-base design for any trafficked surface.
About 40-50 mm for a decorative surface over a membrane, and 75-100 mm or more for a trafficked drive, usually over a separate compacted sub-base.
Density depends on the stone type, grading and moisture. Angular limestone chippings run heavier than lightweight or rounded aggregate — 1.4-1.8 t/m³ covers most products. Use the figure on your supplier's data sheet.
A smaller one. Loose decorative gravel barely consolidates, so 5-10% is enough; a compacted sub-base can lose 15-25% of its loose volume.