About the Mulch Calculator
This mulch calculator works out how much material you need to cover a garden bed to a chosen depth. Enter the length, width and depth, and it returns the volume in cubic yards and cubic feet, or cubic metres and litres, and the number of bags if you tell it the bag size. It works for bark, wood chips, compost, topsoil and any other loose material that is spread to a depth. You can work in feet and inches or metres and centimetres, and see the answer in both systems.
Updated October 2026
How to use the Mulch Calculator
- 1Choose feet and inches, or metres and centimetres.
- 2Enter the length and width of the bed.
- 3Enter the depth you want, such as 3 inches or 8 centimetres.
- 4Enter the bag size if you buy bags, or leave it empty for loose material.
- 5Read the volume and the number of bags, then press Copy result.
Why depth matters
Mulch does several jobs: it holds moisture in the soil, keeps weeds from sprouting, protects roots from heat and cold, and slowly feeds the soil as it breaks down. Most of these benefits need a layer thick enough to block light but thin enough to let air and water through. That is why the depth you enter is the biggest factor in how much you need.
Quick coverage guide
- 2 inches deep: about 162 sq ft per cubic yard
- 3 inches deep: about 108 sq ft per cubic yard
- 4 inches deep: about 81 sq ft per cubic yard
- 5 cm deep: about 20 m² per cubic metre
- 8 cm deep: about 12.5 m² per cubic metre
Bags or loose
Bags are convenient for small jobs, and the bag size is printed on the front, usually in cubic feet or litres. For larger beds, ask a local supplier for a delivery by the cubic yard or cubic metre, which often costs less per unit. Check the delivered volume is measured loose, and have a tarp ready where it will be dropped.
Related tools
The Gravel Calculator and Concrete Calculator size other bulk materials, the Area Calculator and Volume Calculator help with odd shapes, and the Unit Converter changes between cubic feet, yards, metres and litres. The Tile Calculator and Paint Calculator cover indoor projects.
Features
- Cubic yards and cubic feet, or cubic metres and litres
- Number of bags from the bag size
- Shows the answer in both unit systems
- Works for mulch, compost, topsoil and bark
- Checks for unrealistic depths
- Runs in your browser
Frequently asked questions
How do I calculate how much mulch I need?
Multiply the length by the width to get the area, then by the depth. For feet and inches, divide the depth in inches by 12. A 10 by 10 foot bed at 3 inches deep is 100 × 0.25 = 25 cubic feet, or about 0.93 cubic yards. The calculator does the conversion.
How deep should mulch be?
Two to three inches (5 to 8 centimetres) is typical for flower beds and around shrubs. Too thin lets weeds through, while piling it thicker than about four inches can hold too much moisture. Keep mulch a few inches away from tree trunks and plant stems.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cubic feet each. Loose mulch bought by the cubic yard from a landscape supplier is usually cheaper than bags if you need more than a yard or two.
How many square feet does a cubic yard of mulch cover?
At 3 inches deep a cubic yard covers about 108 square feet, at 2 inches about 162 square feet and at 4 inches about 81 square feet. Enter your own bed to get a figure for your own depth.
Can I use it for compost or topsoil?
Yes. Any material spread to a depth uses the same volume sum. Compost is often applied at 1 to 2 inches, and topsoil at 4 inches or more for new lawns and raised beds. Adjust the depth accordingly.
Should I buy extra?
Mulch settles and breaks down, and beds are rarely perfectly flat. Rounding up to a whole bag, which the calculator does, is usually enough. If you are filling an uneven area, add 5 to 10 percent.