What this calculator does
The mulch calculator estimates the volume needed to cover a rectangular bed or planting area. It reports raw volume, volume after allowance, cubic yards for bulk orders, and whole bag counts when a bag size is selected.
Formula overview
The calculator converts length, width, and depth to feet, then multiplies length by width by depth. Cubic feet are divided by 27 to convert to cubic yards.
Bags and bulk mulch
Bag counts are based on the volume after allowance divided by the selected bag size. The purchase recommendation rounds up because partial bags are not normally orderable.
Worked example
A 20 ft by 10 ft bed at 3 inches deep is 200 square feet. A 3 inch depth is 0.25 ft, so the raw volume is 50 cubic feet, or about 1.85 cubic yards. With a 10% allowance, the estimate is 55 cubic feet, about 2.04 cubic yards, or 28 two-cubic-foot bags.
Assumptions and limitations
Mulch is treated as a volume material. This estimate does not account for irregular bed shapes, settling over time, or supplier-specific bag fill tolerances.