Mulch Calculator
Mulch keeps roots cool, slows weeds and locks in moisture — but only at the right depth. Enter your bed area and target depth to see how many cubic yards (for bulk delivery) or 2 cu ft bags (for store pickup) you need.
Your answer
- 2 cu ft Bags
- 13
- Cubic Feet
- 25
How it works
Formula
Cubic Feet = Area × (Depth ÷ 12) • Cubic Yards = Cu Ft ÷ 27 • Bags = ceil(Cu Ft ÷ 2)
Worked example
A 100 ft² bed at 3 in deep = 25 ft³ → 0.93 yd³, or 13 bags of 2 cu ft mulch.
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How much mulch do I need?
Mulch is a simple volume calculation: bed area × depth, converted to cubic feet or cubic yards. Bagged mulch is sold in 2-cubic-foot bags; bulk mulch is sold by the cubic yard (27 cubic feet). At 3 inches deep — the sweet spot for weed suppression and moisture retention — one cubic yard covers 108 square feet, and one 2-cu-ft bag covers about 8 square feet.
Right depth by use case
Vegetable and annual beds: 1–2 inches so seeds and transplants can push through. Established perennial beds: 2–3 inches. New beds or heavy weed pressure: 3–4 inches. Around shrubs and trees: 2–3 inches, kept 3 inches back from the trunk (never volcano-mulch a tree). Playgrounds: 6–12 inches of engineered wood fiber for ASTM fall-height ratings.
Bags vs bulk — where the crossover is
Bagged mulch is convenient and clean but roughly twice the price per cubic foot of bulk. The break-even is around 3–5 cubic yards (40–70 bags): below that, bags win on convenience; above it, bulk delivery is faster, cheaper and saves you loading 40+ plastic bags. If you have a driveway a truck can dump on and a wheelbarrow, always go bulk for a full landscape refresh.
Worked example
A 30 ft × 8 ft front foundation bed at 3 inches: 30 × 8 × (3 ÷ 12) = 60 ft³ = 2.22 yd³. That is 30 bags of 2-cu-ft mulch, or a 2.5-yard bulk delivery. At $4 per bag ($120) vs $60 per bulk yard delivered ($150), bags are slightly cheaper here — but at 5 yards the numbers flip decisively in favor of bulk.
Frequently asked questions
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