Gravel Quantity
Free Gravel Quantity calculator with clear step-by-step results.
About Gravel Quantity
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.
Formulas
Volume
Volume = area × depth ÷ 1000, then × (1 + compaction allowance)
Mass
Tonnes = order volume × bulk density
Worked example
With the default values below, Gravel Quantity returns Gravel to Order of 1.84. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Area to coverminimum 0 m²
- 20 m²
- Finished depthminimum 1 mm
- 50 mm
- Bulk densityminimum 0.1 t/m³
- 1.6 t/m³
- Compaction and settlement allowanceaccepts 0–60 %
- 15 %
Results
- Gravel to Order
- 1.84 t
- Volume at Finished Depth
- 1.000 m³
- Volume Including Allowance
- 1.150 m³
- Bulk Bags (0.6 m³)
- 2 bags
Step by step
- 1Values used
- 2Volume
- 3Mass
- 4Gravel to Order= 1.84 t
- 5Volume at Finished Depth= 1.000 m³
- 6Volume Including Allowance= 1.150 m³
- 7Bulk Bags (0.6 m³)= 2 bags
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- Quantities are planning estimates. Confirm bulk density and coverage with your supplier, and follow the drainage and sub-base design for any trafficked surface.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Quantities are planning estimates. Confirm bulk density and coverage with your supplier, and follow the drainage and sub-base design for any trafficked surface.
Frequently Asked Questions
What depth should I use?
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.
Why does bulk density vary?
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.
Should I add the compaction allowance for decorative gravel?
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.