A 320 sq. ft. bed at a depth of 3 inches needs approximately 3 cubic yards of mulch, or about 40 standard 2 cu. ft. bags. Bulk delivered mulch runs $105–$135; bagged mulch runs $140–$200. Use the mulch calculator for exact figures.
The unit trap
Bags are labeled in cubic feet. Bulk mulch is sold in cubic yards (27 cu. ft. = 1 cubic yard). A 2 cu. ft. bag of mulch is 1/13.5 of a cubic yard, and there are 13.5 bags per cubic yard—the number every landscaper has committed to memory.
What our data shows
Across recent MaterialCalc mulch jobs, the median bed area is 320 sq. ft., and users consistently choose a 3-inch depth. About one in eight users return and rerun the calculation after ordering, usually because they measured only the visible bed area and forgot the strip along the driveway.
The formulas
cubic_yards = (sq_ft × depth_in ÷ 12) ÷ 27 bags = cubic_yards × 13.5 (assuming 2 cu. ft. bags)
Coverage table
Depth | Sq. ft. per cubic yard | Sq. ft. per 2 cu. ft. bag 1" | 324 | 24 2" | 162 | 12 3" | 108 | 8 4" | 81 | 6
Worked example
Front-yard bed: 12' × 25' plus a 2' × 40' strip along the walkway = 300 + 80 = 380 sq. ft. at a depth of 3 inches:
380 × (3 ÷ 12) = 95 cu. ft.
95 ÷ 27 = 3.52 cu. yd. → order 3.5 cubic yards in bulk or approximately 48 bags
Common mistakes
Mulch volcanoes. Piling mulch against a tree trunk rots the bark and invites voles. Keep a 2–3-inch bare ring around each trunk.
Too deep. Six inches of mulch suffocates fine roots and holds water against stems—cap the depth at 4 inches.
Skipping edging. Mulch migrates onto lawns and driveways without a defined edge; a $30 spade-cut edge lasts a full season.
Cheap dyed mulch in food gardens. Use natural hardwood or leaf mulch around anything edible—dyed mulches sometimes conceal CCA-treated pallet wood.
Bulk vs. bags (2026 pricing)
Format | Typical price | Break-even point 2 cu. ft. bag (hardwood) | $3.50–$4.99 | — Bulk cubic yard (hardwood) | $35–$55 delivered | Bulk wins above approximately 3 cu. yd. Dyed mulch (bag) | $4.00–$5.50 | — Bulk delivery fee | $65–$120 flat | Amortizes quickly at 5+ cu. yd.
Get exact numbers
The mulch calculator accepts multiple bed shapes, converts between bags and cubic yards, and accounts for the depth you plan to install.