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Mulch Calculator: Cubic Yards and Bags
Find out how much mulch you need for your garden beds, in cubic yards for bulk delivery or in 2 cu ft bags, for any depth.
How much mulch do I need?
Multiply the bed's area in square feet by the depth in inches, divide by 12 to get cubic feet, then by 27 to get cubic yards. A 20 × 4 ft bed at 3 inches deep is 80 × 3 ÷ 12 = 20 cu ft, or 0.74 cu yd. That is 10 bags of 2 cu ft.
A quick rule: one cubic yard of mulch covers about 108 sq ft at 3 inches deep, or 162 sq ft at 2 inches.
How deep should mulch be?
Most extension services recommend 2 to 3 inches of wood mulch, and up to 4 inches for coarse bark. Thinner layers don't stop weeds; thicker layers can keep water and air from reaching roots. Keep mulch a few inches away from tree trunks and plant stems, never piled up like a volcano.
If you are topping up last year's mulch, 1 to 2 inches is usually enough.
Bags or bulk?
Bagged mulch normally comes in 2 cu ft bags, so 13.5 bags make one cubic yard. At $3 to $5 a bag, a yard in bags costs $40 to $70, while bulk mulch is often $25 to $45 a yard plus delivery. Bags are easier for a few beds; bulk is cheaper once you need 2 yards or more.
Frequently asked questions
How many bags of mulch are in a yard?
13.5 bags of 2 cu ft make one cubic yard (27 cu ft).
How much area does a yard of mulch cover?
One cubic yard covers about 108 sq ft at 3 in deep, 162 sq ft at 2 in, or 324 sq ft at 1 in.