About this tool
The Mulch Calculator tells you how much mulch to buy for a bed or area, in cubic yards and cubic feet, plus the number of bags and the cost. Enter the area directly in square feet or switch to length × width, set the depth in inches, choose your bag size, and optionally a price per bag; it all computes live in your browser.
The volume is area × (depth ÷ 12) to convert the depth from inches to feet, giving cubic feet. Cubic yards are that volume ÷ 27 (there are 27 cubic feet in a cubic yard). The number of bags is the volume divided by the bag size, rounded up: bags = ⌈volume ÷ bag size⌉, so you never come up short. If you enter a price per bag, the cost is bags × price.
A depth of 2–3 inches is common for decorative beds and 3–4 inches for weed suppression. Because bags are always rounded up to whole units, ordering exactly the shown number leaves a small margin for settling and uneven ground.