How Much Soil Do I Need?
Filling a raised garden bed requires calculating the exact volume of the bed in cubic feet or cubic yards. Soil is typically sold by the cubic yard for bulk delivery, or in 1.5 to 2 cubic foot bags at retail stores.
To skip the math, use our free Soil Calculator.
The Raised Bed Formula
Measure the inside dimensions of your raised bed.
Cubic Feet = Length (ft) × Width (ft) × Depth (ft)
If you have a standard 4 ft by 8 ft bed that is 1 foot deep:
4 × 8 × 1 = 32 cubic feet
Converting to Bags and Yards
To convert cubic feet to cubic yards, divide by 27:
32 ÷ 27 = 1.18 cubic yards
To convert to bags, divide by the bag size. If buying 1.5 cubic foot bags of organic garden soil:
32 ÷ 1.5 = 21.3 (Order 22 bags)
Accounting for Settling
Soil contains organic matter and air pockets. When it rains, or when you water the bed, the soil will settle and compact. It is highly recommended to add an extra 5% to 10% to your calculation so that the bed remains full after the first few weeks.