Mulch & Soil Calculator
Cubic yards and bags of mulch, soil or compost.
How it’s calculated
Cubic feet = area (sq ft) × depth (in) ÷ 12 × (1 + waste%). Cubic yards = cubic feet ÷ 27. Bags = cubic feet ÷ bag size, rounded up.
Bag sizes vary (2 cu ft is common for mulch; soil is often 0.75–1.5 cu ft) — enter the size printed on your bag.
Worked examples
10×10 ft bed at 3 in: 100 × 3 ÷ 12 = 25 cu ft = 0.93 cu yd; +5% = 26.25 cu ft → 14 bags of 2 cu ft.
Round bed, 8 ft diameter, 2 in: area = 3.1416 × 4² = 50.3 sq ft; × 2 ÷ 12 = 8.4 cu ft → 5 bags at 2 cu ft (with 5%).
Waste factor
Mulch and soil settle and compact after spreading. A 5–10% cushion is a reasonable rule of thumb (not a manufacturer figure); use more for loose, fluffy material.
Common mistakes
- Entering depth in feet instead of inches.
- Assuming every bag is 2 cu ft: soil and compost bags are often smaller, so use the size printed on the bag.
- Comparing bulk and bagged prices without converting: 1 cubic yard = 27 cubic feet.
FAQ
Bulk or bags?
Bulk is sold by the cubic yard; compare price per cubic yard (27 cu ft) against bags.
How deep should mulch be?
Follow your local extension service; many recommend a few inches and keeping mulch away from trunks.
Can I use this for gravel?
Yes for volume, but gravel is sold by weight too — ask your supplier for its tons per cubic yard.
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