Soil Volume Calculator
Whether you are topdressing a lawn, filling garden beds, or landscaping a new yard, knowing how much soil to order prevents waste and extra trips to the store. This calculator converts the dimensions of your project area (length, width, and desired depth) into the total volume of soil needed, expressed in cubic feet and cubic yards. It also estimates how many 40-lb and 50-lb bags you would need, based on the standard coverage of 0.75 cubic feet per 40-lb bag. You can enter either length and width together, or enter the total area in square feet directly. For lawn topdressing, typical depths range from 0.25 to 0.5 inches. For new lawn establishment, 4 to 6 inches is recommended by most cooperative extension services. For raised beds and garden plots, 8 to 12 inches is common. When ordering in bulk, always round up to the nearest quarter cubic yard to ensure you have enough material. Soil settles after application, so add 10 to 15 percent extra for large projects.
Soil volume formula
Cubic feet = Length (ft) x Width (ft) x Depth (ft) x (1 + Extra/100)
Cubic yards = Cubic feet / 27
40-lb bags = Ceiling(Cubic feet / 0.75)
50-lb bags = Ceiling(Cubic feet / 1.0)
Worked example
Area: 20 ft x 15 ft, depth 4 inches, 10% extra for settlement.
- Depth in feet = 4 / 12 = 0.333 ft
- Base volume = 20 x 15 x 0.333 = 100 cu ft
- With 10% extra = 100 x 1.10 = 110 cu ft
- Cubic yards = 110 / 27 = 4.07 cu yd
- 40-lb bags = Ceiling(110 / 0.75) = 147 bags
- 50-lb bags = Ceiling(110 / 1.0) = 110 bags
Frequently asked questions
How many bags of soil do I need?
A standard 40-lb bag of topsoil covers about 0.75 cubic feet. Divide your total cubic footage by 0.75 to get the number of 40-lb bags. A 50-lb bag typically covers 0.75 to 1 cubic foot. Check the bag for the exact coverage volume.
How do I convert cubic feet to cubic yards?
Divide cubic feet by 27. There are 27 cubic feet in one cubic yard (3 ft x 3 ft x 3 ft). For example, 54 cubic feet equals 2 cubic yards.
How much does a cubic yard of topsoil weigh?
A cubic yard of loose topsoil typically weighs about 1,000 to 1,100 lb (approximately 0.5 tons). Wet or compacted soil can weigh significantly more. Verify with your supplier before transport.
How deep should I apply topsoil to a lawn?
For lawn repair and overseeding, a 1/4 inch to 1/2 inch layer is typical. For new lawn establishment, 4 to 6 inches of quality topsoil is recommended. For garden beds, 6 to 12 inches provides the best growing conditions.
Is bulk topsoil or bagged soil more economical?
Bulk topsoil delivered by the cubic yard is almost always more cost-effective for quantities over 2 to 3 cubic yards. Bagged soil is convenient for small projects but costs significantly more per cubic foot. Compare prices per cubic yard when shopping.
Sources
- University of Minnesota Extension: Soil and fertilizer guidance.
- USDA Natural Resources Conservation Service: soil basics.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. Bag coverage varies by product. Check the label before purchasing.