Mulch Calculator
Free mulch calculator: how much mulch you need for a garden bed from its size and depth, in cubic yards or cubic metres, and how many bags to buy.
A layer of 5 to 8 cm (2 to 3 inches) of mulch keeps moisture in and weeds down; thicker layers can starve the soil of air. Mulch settles after a few weeks, so many gardeners add a little extra.
Also: Gravel Calculator · Concrete Calculator · Square Footage Calculator
What it does
The volume is the area times the depth. Gravel and sand are often sold by weight, so the calculator also multiplies by a typical loose density: about 1.6 t/m³ for gravel and sand, 1.25 for topsoil and 0.4 for bark mulch. Your supplier’s figure, if you have it, is more accurate.
How to use it
- Choose the material and enter the length and width of the area.
- Enter the depth of the layer.
- Read the volume, the weight and the number of bags; change the density if your supplier gives one.
The arithmetic runs in your browser. Nothing you type is sent anywhere and nothing is stored, so you can use these with real numbers.
Frequently asked questions
How deep should a gravel layer be?
About 5 cm (2 inches) for a path or decorative bed, and 10 to 15 cm (4 to 6 inches) for a driveway, usually over a compacted base layer.
Why does the weight differ between suppliers?
Density depends on the stone, the grain size and how wet the material is. Wet sand can weigh 20% more than dry sand, so use the density your supplier quotes when you buy by weight.