Topsoil Calculator
Enter the length and width of the area, choose your preferred units, and enter the desired topsoil depth. The calculator estimates your required volume in cubic feet and cubic yards.
Topsoil Calculator
Find out how much topsoil you need for lawns, gardens, flower beds, landscaping and other outdoor projects. Calculate cubic feet and cubic yards from your area and desired soil depth.
Bulk topsoil is commonly sold by the cubic yard. This calculator converts your measurements into cubic feet and cubic yards so you can compare your result with supplier quantities.
Planning to add topsoil to a lawn, garden, flower bed, or landscaping project? The amount you need depends on the area you want to cover and the depth of topsoil you plan to add.
Our Topsoil Calculator gives you a quick estimate of the amount of topsoil required, helping you decide how much to order before you start your project.
It is useful for everything from spreading a thin layer over an existing lawn to filling garden beds with several inches of fresh soil.
What does a Topsoil Calculator do?
A topsoil calculator converts the dimensions of an area and the desired soil depth into an estimated volume of topsoil.
For a simple rectangular area, the calculation is:
Length × Width × Depth = Volume
Because topsoil is commonly sold by the cubic yard, the result can then be converted from cubic feet to cubic yards.
1 cubic yard = 27 cubic feet
For example, suppose you have a lawn that is 30 feet long and 20 feet wide and you want to add 3 inches of topsoil.
First, convert the depth to feet:
3 inches ÷ 12 = 0.25 feet
Then:
30 × 20 × 0.25 = 150 cubic feet
Finally:
150 ÷ 27 = 5.56 cubic yards
So you would need approximately 5.6 cubic yards of topsoil before allowing for any extra material.
How Much Topsoil Do I Need?
There isn’t one standard amount of topsoil that every project requires. The right depth depends on what you are trying to accomplish.
Typical projects may include:
| Project | Common topsoil depth |
|---|---|
| Light lawn topdressing | ¼–½ inch |
| Lawn improvement | 1–2 inches |
| New lawn preparation | 4–6 inches |
| Flower beds | 6–12 inches |
| Vegetable gardens | 8–12+ inches |
| Filling raised beds | Depends on bed depth |
| General landscaping | 2–6 inches |
These are useful starting points rather than strict rules. Existing soil, drainage, plants, grading, and the type of project can all change the amount that makes sense.
If you’re trying to improve an existing lawn, for example, spreading several inches of soil over the entire surface may be unnecessary. A relatively thin layer can be enough for topdressing, while a new planting area may require considerably more.
How to Use the Topsoil Calculator
You don’t need to calculate the volume manually.
1. Measure the length
Measure the longest dimension of the area you want to cover.
For a rectangular garden that is 25 feet long, enter 25 ft.
2. Measure the width
Measure the width of the same area.
If the garden is 12 feet wide, enter 12 ft.
3. Choose the topsoil depth
Decide how deep you want the new topsoil layer to be.
For example, if you want 4 inches:
Depth = 4 inches
4. Calculate
The calculator determines the volume of soil required.
You’ll receive the result in cubic feet and cubic yards, making it easier to compare your calculation with soil suppliers’ quantities.
Topsoil Calculator Formula
For a rectangular area, use:
Topsoil volume = Length × Width × Depth
The important part is making sure all three measurements use the same unit.
If your measurements are in feet and your depth is in inches, convert the depth first:
Depth in feet = Depth in inches ÷ 12
Then calculate:
Length × Width × Depth in feet = Cubic feet
To convert cubic feet to cubic yards:
Cubic yards = Cubic feet ÷ 27
Example
Imagine a 40 ft × 15 ft garden where you want 6 inches of topsoil.
Convert 6 inches to feet:
6 ÷ 12 = 0.5 ft
Calculate the volume:
40 × 15 × 0.5 = 300 cubic feet
Convert to cubic yards:
300 ÷ 27 = 11.11 cubic yards
You would therefore need approximately 11.1 cubic yards of topsoil.
Why Topsoil Depth Matters
Two areas with exactly the same length and width can require dramatically different amounts of soil.
Consider a 1,000-square-foot lawn.
At a depth of only 1 inch, the required volume is about:
3.09 cubic yards
At 4 inches:
12.35 cubic yards
At 6 inches:
18.52 cubic yards
That’s why entering the correct depth is just as important as measuring the area.
If you’re unsure what depth to use, think about the purpose of the soil rather than simply choosing a larger number. A lawn that needs a light topdressing has very different requirements from a new garden bed.
How Many Bags of Topsoil Do I Need?
Topsoil is sold in different bag sizes, so the number of bags depends on the volume of each bag.
For example, suppose your project requires 2 cubic yards.
Since:
1 cubic yard = 27 cubic feet
you need:
2 × 27 = 54 cubic feet
If each bag contains 1 cubic foot:
54 ÷ 1 = 54 bags
If each bag contains 0.75 cubic feet:
54 ÷ 0.75 = 72 bags
This is one reason bulk topsoil can become more practical for larger landscaping projects.
Always check the actual volume printed on the bag rather than assuming all bags contain the same amount.