What Is the Soil Volume Calculator?
This calculator estimates how much soil you need to fill a raised garden bed, planter, or growing area. Enter the bed dimensions and the desired soil depth, and it returns the volume in cubic feet, cubic yards, cubic meters, liters, and the approximate number of standard bags. It works for any region and uses simple geometry, so no country-specific assumptions apply.
How to Use It
Measure the inside length and width of your bed in feet, and choose how deep you want the soil in inches. Enter the number of identical beds you are filling. The tool multiplies the dimensions to find total volume and converts it into the units most useful for buying soil.
The Formula
Because depth is usually given in inches while length and width are in feet, the depth is divided by 12 to convert to feet before multiplying:
$$V = L \times W \times \frac{D}{12} \times N$$where \(L\) = bed length in feet, \(W\) = width in feet, \(D\) = soil depth in inches, and \(N\) = number of beds. Cubic yards come from dividing by 27, and a standard 40 lb bag holds roughly \(0.75\,\text{ft}^3\).
Worked Example
For an 8 ft by 4 ft bed filled 12 in (1 ft) deep:
$$V = 8 \times 4 \times \frac{12}{12} \times 1 = 32\,\text{ft}^3$$That equals \(\tfrac{32}{27} \approx 1.19\,\text{yd}^3\), about \(906\,\text{L}\), or roughly \(\tfrac{32}{0.75} \approx 42.7\) bags.
FAQ
How deep should garden soil be? Most vegetables thrive with 8–12 inches of loose soil; deep-rooted crops prefer 12–18 inches.
How many bags do I need? Divide total cubic feet by the bag size on the label. This tool assumes 0.75 ft³ per bag, a common size for a 40 lb bag.
Should I round up? Yes — soil settles after watering, so order about 10% extra to top off your beds.
