Gravel, Topsoil and Bark Calculator
Pick the material, enter the size of the area and the depth. You get the volume, the weight and the number of bags and bulk bags to buy.
This is an estimate. Suppliers quote weights that vary with moisture and stone size, so use theirs if you have it.
Worked examples
A gravel path
10 square metres, 50 mm deep, 1.6 tonnes a cubic metre, 5% waste
0.525 cubic metres, 0.84 tonnes, 34 bags of 25 kg
525 litres is 11 bags of 50 litres.
Topsoil for a lawn
24 square metres, 150 mm deep, 1.4 tonnes a cubic metre, 5% waste
3.78 cubic metres, 5.3 tonnes
Order by the tonne or in bulk bags.
About Gravel, Topsoil and Bark Calculator
This calculator works out how much loose material you need for a path, drive, border, lawn or play area. Choose the material, enter the size of the area as a rectangle, a circle or a known area in square metres, and the depth you want to spread it. It gives the volume in cubic metres and litres, the weight in tonnes, and the number of bags and bulk bags to buy.
Each material has a typical depth and weight filled in for you, such as 50 mm and 1.6 tonnes a cubic metre for gravel, 100 mm and 2.1 tonnes for crushed stone sub-base, and 150 mm and 1.4 tonnes for topsoil. Change them if your supplier gives different figures. An allowance for waste covers material that settles or is spilled. Bark and compost are sold by volume, so the weight can be left at zero.
How to use Gravel, Topsoil and Bark Calculator
- Pick the material and choose metric or imperial units.
- Enter the size of the area, as a rectangle, a circle or a known area.
- Check the depth and the weight, and adjust the allowance for waste.
- Read the volume, tonnes and bags, and order from your supplier.
Common uses
- A gravel path or drive
- Spreading topsoil before laying a lawn
- Mulching borders with bark
- Ordering sand or stone under paving
Frequently asked questions
How much gravel do I need for 10 square metres?
At 50 mm deep, 10 square metres needs 0.5 cubic metres, or 0.525 with 5% waste. At 1.6 tonnes a cubic metre that is 0.84 tonnes, which is 34 bags of 25 kg or one bulk bag.
How deep should gravel be?
A layer of 40 to 50 mm is normal for a path or drive. Put it over a weed membrane on a compacted base, and use larger stone and a thicker layer where there is heavy traffic.
How much topsoil for a new lawn?
Spread 100 to 150 mm. A lawn of 24 square metres at 150 mm needs 3.6 cubic metres, or 3.78 with 5% extra, which is about 5.3 tonnes at 1.4 tonnes a cubic metre.
How thick should bark mulch be?
A layer of 50 to 75 mm suppresses weeds and keeps moisture in. It breaks down, so top it up every year or two.
Why do suppliers quote different weights?
Weight depends on the moisture, the grading and how well the material is compacted. The figures are typical. Ask your supplier for their number and type it in.