Free tool
Gravel and soil calculator for the garden
Enter the area and the depth, and you will know how many cubic metres, tonnes and bags to order. Everything is calculated in your browser: nothing is sent.
For a gravel path about 5 cm is usually enough, on a firm base with a weed membrane.
How we calculate
- Volume: area × depth. 20 m² at 5 cm is 1 m³.
- Margin: we add 10 % for waste and for what compacts when spread.
- Weight: volume × density. It changes with moisture and the specific material: use the figure on your supplier’s data sheet if you have it.
- Bags: we divide by 25 kg bags, or 50 litre bags for soil and bark, and round up. Check the format your supplier sells.
What the calculator does not do
It gives a rough quantity for an area of even depth. It is not for deep fill, for the back of a retaining wall or for foundations: the project’s qualified professional decides those. It does not give prices either, which depend on the supplier and transport.
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Frequently asked questions
How much gravel do I need for 10 m²?
At a depth of 5 cm it is 0.5 m³, about 0.55 m³ with margin. At 1.6 t/m³ that is about 0.9 tonnes.
How much does a cubic metre of gravel weigh?
As a rough figure, about 1,600 kg. It varies with the stone size and moisture, and your supplier can give you the exact figure.
How deep should topsoil be for a lawn?
As a guide, 15 to 20 cm of good soil. It depends on the ground you start from.
How do I convert cubic metres to bags?
Multiply the m³ by 1,000 to get litres and divide by the litres in the bag. One cubic metre is 20 bags of 50 litres.