How much gravel do I need?
The amount of gravel you need depends on three main measurements: the length of the area, its width and the depth of the gravel layer. AmountHub's gravel calculator uses these measurements to estimate the total volume and approximate weight of gravel required for your project.
Enter the dimensions of your driveway, garden path, patio or landscaping area and choose either metric or imperial units. The calculator converts the measurements automatically and estimates the result in cubic metres and tonnes, or cubic yards and US tons.
For smaller projects, the result is also displayed in kilograms or pounds so that you do not have to convert a small fraction of a tonne yourself.
How the gravel calculator works
Gravel quantity is calculated by first finding the volume of the area. For a rectangular area, the basic calculation is:
Length × Width × Depth = Gravel Volume
The volume is then multiplied by an estimated density for the selected gravel type. Different materials have different densities, so pea gravel, crushed stone and river rock may produce slightly different weight estimates even when the volume is the same.
By default, the calculator adds 10% extra material. This allowance can help account for uneven ground, settling, compaction and small losses during delivery or installation. You can disable the extra allowance if you prefer to calculate the exact theoretical quantity.
Gravel calculation example
Imagine you are creating a garden path that is 10 metres long, 2 metres wide and 5 centimetres deep.
The area is 20 m² and the gravel volume before adding extra material is approximately 1 m³.
Using a general gravel density of roughly 1.7 tonnes per cubic metre, the project would require around 1.7 tonnes of gravel before any additional allowance.
With a 10% allowance included, the estimated requirement becomes approximately 1.87 tonnes.
How deep should gravel be?
The correct gravel depth depends on how the area will be used. Decorative gravel normally requires a much shallower layer than a driveway or structural base.
| Project | Typical gravel depth |
|---|---|
| Decorative garden gravel | 3–5 cm |
| Garden path | About 5 cm |
| Patio or seating area | About 5–8 cm |
| Driveway surface layer | About 5–10 cm |
These figures are general planning estimates. Projects that carry vehicles or require drainage and structural support may need additional compacted base layers underneath the visible gravel.
How much does a cubic metre of gravel weigh?
Gravel does not have one exact weight because the density changes depending on stone size, material, moisture and how tightly it is compacted.
As a general estimate, many common gravel types weigh around 1.6 to 1.8 tonnes per cubic metre. Our calculator uses a different estimated density depending on the gravel type you select.
- General gravel: approximately 1.70 tonnes per m³
- Pea gravel: approximately 1.60 tonnes per m³
- Crushed stone: approximately 1.75 tonnes per m³
- River rock: approximately 1.65 tonnes per m³
If your supplier provides a specific density for the product you plan to purchase, their figure should always be considered more accurate for that particular material.
Should I order extra gravel?
Ordering slightly more gravel than the mathematical minimum can be useful. Ground is rarely perfectly level, measurements may not be exact, and gravel can settle or compact after installation.
A 10% allowance is a simple general estimate, which is why it is enabled by default in the calculator. For a very precisely prepared area you may need less extra material, while irregular or sloped ground could require more.
Frequently asked questions
Can I use this calculator for a driveway?
Yes. Enter the driveway length, width and planned gravel depth. Remember that driveways may also require compacted foundation layers underneath the final gravel surface.
Can I calculate gravel in centimetres?
Yes. Metric length and width measurements can be entered in metres or centimetres, while gravel depth can also be entered in centimetres.
Does the calculator support feet and inches?
Yes. Switch to Imperial to enter measurements in feet or inches. Results are displayed in cubic yards, US tons and pounds.
Why does gravel weight vary?
Different stone types have different densities. Moisture, stone size and compaction can also change the actual weight of a given volume of gravel.
Can I estimate the cost of gravel?
Yes. Enter the price per tonne or US ton in the optional price field and the calculator will estimate the material cost based on the calculated weight.