Free Mulch Quantity calculator with clear step-by-step results.
Bulk mulch is sold by the cubic yard and bagged mulch by the cubic foot, so the useful answer is both. Bed area times depth in feet gives cubic feet; dividing by 27 converts to cubic yards. One cubic yard covers about 160 ft² at 2 inches or 108 ft² at 3 inches. A settling allowance is included because shredded bark loses noticeable loft in the first few weeks.
Volume
Cubic feet = area (ft²) × depth (in) ÷ 12 × (1 + settling)
Bulk and bags
Cubic yards = cubic feet ÷ 27; bags = ceil(cubic feet ÷ bag size)
Coverage figures are approximate and vary with material, moisture and how firmly the mulch is spread. Confirm volumes with your supplier before ordering bulk loads.
Two to three inches is the usual recommendation. Deeper than about four inches can hold water against stems and starve roots of air, and mulch should be kept clear of trunks rather than mounded against them.
Thirteen and a half 2 ft³ bags, or nine 3 ft³ bags. Bulk delivery is almost always cheaper above roughly two cubic yards.
Organic mulches break down, so most beds need a thinner refresh layer each season rather than a full re-mulch. Measure the depth you already have and only make up the difference.