Depth drives the orderThe same bed needs three times as much material at 3 inches deep as it does at 1 inch deep.
Bulk mulch formula
Multiply bed length by width, multiply by depth in feet, and divide by 27. The result is cubic yards. For several beds, calculate each section and add the volumes before rounding for delivery.
- One cubic yard covers 324 sq ft at 1 inch deep.
- One cubic yard covers 162 sq ft at 2 inches deep.
- One cubic yard covers 108 sq ft at 3 inches deep.
Bags or bulk delivery?
Bagged mulch is convenient for small or hard-to-reach areas. Bulk can be simpler for larger projects, but delivery fees and the drop location matter. Enter the cubic feet printed on the bag and compare the total delivered cost locally.
Do not bury trunks or stems
Keep mulch away from tree trunks and plant crowns, and do not keep stacking fresh material over a deep old layer. The calculator estimates volume; plant-specific depth and site drainage still need judgment.
BuildMath Lab provides planning estimates, not engineering, code approval, or a supplier quote. Confirm the final order with the product manufacturer, supplier, plans, and qualified professional.