CalculateY
Quick Answer
A 10 x 20 foot area at 3 inches deep requires approximately 1.85 cubic yards of mulch, or 25 bags of 2-cubic-foot mulch.
Common Examples
| Input | Result |
|---|---|
| 10 x 20 ft, 3 in deep, mulch | 50 cu ft, 1.85 cu yd, 25 bags (2 cu ft), 0.93 tons |
| 15 x 30 ft, 4 in deep, gravel | 150 cu ft, 5.56 cu yd, 75 bags (2 cu ft), 7.78 tons |
| 8 x 12 ft, 2 in deep, mulch | 16 cu ft, 0.59 cu yd, 8 bags (2 cu ft), 0.30 tons |
| 20 x 20 ft, 6 in deep, soil | 200 cu ft, 7.41 cu yd, 100 bags (2 cu ft), 8.15 tons |
| 6 x 10 ft, 3 in deep, gravel | 15 cu ft, 0.56 cu yd, 8 bags (2 cu ft), 0.78 tons |
How It Works
The Formula
Volume (cubic feet) = Length (ft) x Width (ft) x Depth (in) / 12
Cubic Yards = Cubic Feet / 27
The depth is divided by 12 to convert inches to feet before multiplying with the length and width. The result in cubic feet is then divided by 27 to convert to cubic yards, which is the standard unit for bulk material delivery.
Bag Counts
- 2-cubic-foot bags are the most common retail size for mulch and topsoil
- 3-cubic-foot bags are available for some mulch products
- Bags = ceil(Cubic Feet / Bag Size)
Weight Estimates by Material
Weight varies by material type and moisture content:
- Mulch: approximately 0.5 tons per cubic yard (400 to 600 lbs per yard, varies by type and moisture)
- Gravel: approximately 1.4 tons per cubic yard (2,500 to 3,000 lbs per yard, depending on rock type)
- Topsoil: approximately 1.1 tons per cubic yard (1,800 to 2,200 lbs per yard, depending on moisture)
These weights are estimates. Wet material weighs significantly more than dry material. Gravel weight varies by stone type; for example, pea gravel weighs about 1.4 tons per yard, while crushed limestone is closer to 1.3 tons.
Recommended Depths
- Mulch around plants and trees: 2 to 4 inches. Apply 2 to 3 inches for flower beds and 3 to 4 inches for tree rings and pathways.
- Gravel for walkways: 2 to 3 inches over a compacted base
- Gravel for driveways: 4 to 6 inches total, applied in layers
- Topsoil for lawn repair: 2 to 4 inches, depending on soil quality
Worked Example
For a 15 x 30 foot gravel driveway section at 4 inches deep: Volume = 15 x 30 x (4 / 12) = 15 x 30 x 0.333 = 150 cubic feet. Cubic yards = 150 / 27 = 5.56 cubic yards. Weight = 5.56 x 1.4 = 7.78 tons of gravel. In 2-cubic-foot bags: ceil(150 / 2) = 75 bags. For this quantity, bulk delivery by the cubic yard is more economical than buying individual bags.