How it works
Enter the bed size and how deep you want the mulch, and the calculator returns bulk cubic yards and the number of 2 cubic foot bags, the most common bag size at garden centers.
Two to three inches is the usual depth for weed control and moisture retention. Topping up an existing bed often needs only 1 inch. Keep mulch a few inches away from tree trunks and house siding.
Bulk mulch is usually cheaper once you need more than 2 or 3 cubic yards (27 to 40 bags), even after a delivery fee.
Formula
Cubic feet = length (ft) × width (ft) × depth (in) ÷ 12. Cubic yards = cu ft ÷ 27. Bags = cu ft ÷ 2, rounded up.
Questions people ask
How many bags of mulch are in a yard?
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft or 9 bags of 3 cu ft.
How much area does a yard of mulch cover?
At 3 inches deep, a cubic yard covers about 108 square feet. At 2 inches it covers about 162 square feet.
How deep should mulch be?
Two to three inches for most beds. More than 4 inches can keep water and air from reaching roots; less than 2 inches lets weeds through.