Soil Volume Calculator
Quickly estimate how much topsoil, mulch, or dirt you need for your raised bed, garden, or landscape. Output in cubic yards and standard bags.
Calculator Tool
How to Calculate Soil Volume
Whether you are filling a new raised garden bed, leveling a lawn, or estimating mulch, knowing exactly how much material to buy prevents wasting money or making extra trips to the garden center.
The standard formula used to determine topsoil volume converts all measurements into feet, multiplies them to find cubic feet, and then divides by 27 to find cubic yards.
1. Depth in Feet = Depth in Inches ÷ 12
2. Cubic Feet = Length (ft) × Width (ft) × Depth (ft)
3. Cubic Yards = Cubic Feet ÷ 27
We built this calculator to do the heavy lifting for you automatically, outputting your required materials in both bulk cubic yards and standard 1.5 cubic feet bags.
Example Calculations
Here are a few common gardening scenarios and how the math works out:
4x8 Raised Garden Bed (12" Deep)
4 ft × 8 ft × 1 ft = 32 Cubic ft.
32 ÷ 27 = 1.19 Cubic Yards (or 22 bags of soil)
3x6 Raised Garden Bed (6" Deep)
3 ft × 6 ft × 0.5 ft = 9 Cubic ft.
9 ÷ 27 = 0.33 Cubic Yards (or 6 bags of soil)
Frequently Asked Questions
How many bags of soil do I need for a 10x10 raised bed?
If your raised bed is 10 feet long, 10 feet wide, and 12 inches deep, you will need 3.7 cubic yards of soil. If buying standard 1.5 cubic feet bags, you will need exactly 67 bags.
How do I calculate cubic yards of dirt?
Measure your length and width in feet, and your depth in inches. Multiply Length × Width × (Depth ÷ 12) to get total cubic feet. Then divide that number by 27 to get total cubic yards.
Does this formula work for mulch and compost?
Yes! The soil volume formula computes pure geometric volume. This means it is 100% accurate for estimating mulch, compost, gravel, sand, or any other aggregate material you need for landscaping.