How Much Mulch Do You Need?
Calculate cubic yards of mulch for your garden beds. Enter dimensions and depth — get the exact amount and bag count.
How Much Mulch Do You Need?
The formula: Length (ft) × Width (ft) × Depth (ft) ÷ 27 = cubic yards. A 20×4 foot bed at 3 inches deep needs: 20 × 4 × 0.25 ÷ 27 = 0.74 cubic yards (about 10 bags of 2 cu ft mulch). The standard mulch depth is 3 inches — enough to suppress weeds and retain moisture without suffocating plant roots.
Bagged vs Bulk Mulch
For projects over 3 cubic yards, bulk delivery saves 40-60% compared to bagged. A cubic yard of hardwood mulch costs $30-45 in bulk vs. $60-75 in bags. The break-even point is usually around 2-3 cubic yards. Bulk delivery requires a flat area for dumping and you need to wheelbarrow it to beds yourself.
Best Mulch by Purpose
Hardwood bark: Best all-around for landscape beds. Decomposes slowly, looks professional, $30-45/yard. Cedar: Natural insect repellent, aromatic, lasts longer than hardwood, $40-55/yard. Pine straw: Best for acid-loving plants (azaleas, blueberries), cheapest organic option. Rubber: Permanent but expensive, best for playgrounds. Rock/gravel: Permanent, zero maintenance, but does not improve soil.
The #1 mulching mistake: "volcano mulching" — piling mulch high around tree trunks. This traps moisture against the bark, causes rot, and can kill the tree. Keep a 3-inch gap between mulch and any trunk or stem.
