Mulch depth changes both how the bed performs and how much you need to buy.
How deep
Two to three inches is the usual range for garden beds. That is enough to suppress weeds and hold moisture without smothering the soil.
Coverage
One cubic yard of mulch covers 324 square feet at one inch deep. So at 3 inches, a cubic yard covers about 108 square feet. Bagged mulch is usually 2 cubic feet per bag, and about 13.5 bags equal a cubic yard.
Why not deeper
More than 3 inches can hold too much moisture against stems and roots, and thick mulch piled against trunks invites rot. Keep mulch pulled back a little from stems and trunks.
Estimate your mulch. Mulch Calculator →
Common questions
How deep should mulch be?
Two to three inches for most beds.
How much does a cubic yard of mulch cover?
324 square feet at one inch, or about 108 square feet at three inches.
More Calculators
Concrete New
Enter slab dimensions. Result rounds up with a 7 percent waste allowance.
Gravel New
Enter the area dimensions and depth. Result rounds up with a 5 percent waste allowance.
Mulch New
Enter the bed area and depth. Result rounds up with a 5 percent allowance.
Topsoil New
Enter the area and depth. Result rounds up with a 5 percent allowance.
Paint New
Enter total wall area and coats. Result rounds up to whole units.
Flooring New
Enter room area and the coverage printed on the box. 10 percent waste added.
Tile New
Enter the area and one tile size. 10 percent waste added.
Drywall New
Enter total area to cover. 10 percent waste added.
Paver New
Enter the patio size and one paver size. 5 percent waste added.
Sand New
Enter the area and depth. 5 percent allowance added.
Roofing New
Enter the roof surface area. 10 percent waste added. Three bundles per square.
Insulation New
Enter area to cover and the coverage printed on the package. 5 percent added.
Fence New
Enter total fence length and post spacing.
Sod New
Enter the area to cover. 5 percent allowance added.
Grass Seed New
Enter area and seeding rate. Default rates suit a new lawn.
Fertilizer New
Enter area, target nitrogen rate and the first number on the bag.
Cubic Yards New
Enter length, width and depth. No waste added.
Square Footage New
Enter length and width.
Board Foot New
Enter board dimensions and quantity.
Material Cost New
Enter quantity, unit price, tax and delivery. Figures are in your own currency.