Construction Calculators
Mulch & Topsoil Calculator
Estimate the cubic yards, cubic feet, or bags of mulch or topsoil needed for a garden bed or landscaping project at any depth. Uses the standard landscaping conversion — one cubic yard covers 324 square feet at a 1-inch depth — so the math is exact once you enter your bed size and depth.
Inputs
Material needed
Fill the form and press Calculate.
Where the coverage figure comes from
A cubic yard is 27 cubic feet. Spread one inch deep, that same 27 cubic feet covers 324 square feet (27 ÷ 1/12 ft). That conversion — "one cubic yard will cover a 324-square-foot area with an inch of mulch" — is stated directly by Clemson Cooperative Extension's Home & Garden Information Center mulch factsheet, and it's just arithmetic from there for any other depth: divide square footage by (324 ÷ depth in inches). This calculator uses that exact conversion for both mulch and topsoil, since both are sold and spread by volume the same way.
Bag counts depend entirely on the bag size printed on what you're buying — bagged mulch and soil commonly run 1 to 3 cubic feet depending on the brand and retailer, so there's no single universal figure to bake in. Enter the size from your bag (or your supplier's bulk-yard price) to get an exact bag count.