Gravel Calculator Guide: Cubic Metres, Tonnes and kg
Estimate gravel volume and approximate weight for paths, driveways and landscaping areas using an adjustable material density.
Gravel quantity can be expressed as volume or weight. First calculate the area and finished depth to get cubic metres. If the supplier sells by tonnes, multiply the volume by an appropriate bulk density. Density varies by aggregate type, grading and moisture, so the weight is only an estimate.
Measure the project area
Multiply length by width for a rectangular path, driveway or garden area. Divide irregular spaces into simple sections.
Choose the finished layer depth
Use the intended finished or compacted thickness. If a supplier specifies a loose-fill depth for a target compacted depth, follow that product guidance.
Calculate volume
Multiply area by depth in metres to get cubic metres. Volume is independent of density.
Convert to tonnes
Multiply cubic metres by the selected density in tonnes per cubic metre. Use the supplier’s density where available.
Formula
Gravel volume = length × width × depth. Approximate tonnes = volume × selected density.
Worked example
A 10 m × 3 m area at 0.10 m depth is 3.0 m³. At an assumed density of 1.6 t/m³, the approximate weight is 4.8 tonnes.
Common mistakes to avoid
- Using the wrong depth unit.
- Assuming all gravel has the same density.
- Ignoring compaction or the difference between loose and finished depth.
- Ordering by tonnes without checking the actual product density.
Frequently asked questions
How much gravel do I need for a driveway?
Calculate area × finished depth to get cubic metres, then use the supplier’s bulk density if you need an approximate tonne figure.
What density should I use?
Use the density supplied for the actual gravel product whenever possible.
Is gravel volume the same as tonnes?
No. Weight depends on density, and real bulk density varies with material and moisture.
Use the Gravel Calculator
Enter your project measurements in the calculator, review the result and compare it with the product or supplier information for your specific project.