Calculate exactly how much mulch you need for your garden beds, in cubic yards and bags.
Mulch is sold by volume (cubic yards or cubic-foot bags), not weight, so you need to know the area you're covering and how deep you want the layer to figure out how much to buy. A 2-3 inch layer is typical for most garden beds.
Volume (cubic feet) = Length × Width × (Depth in inches ÷ 12)
Cubic Yards = Volume (cu ft) ÷ 27
A 20ft × 10ft bed at 3" deep needs 20 × 10 × (3/12) = 50 cubic feet, or about 1.85 cubic yards — roughly 25 standard 2 cu ft bags.
Garden bed area multiplied by desired depth, converted to cubic yards or bags.
Commonly 2-4 inches, enough to suppress weeds without smothering roots.
It can trap moisture against bark, promoting rot and pests.