How to use the topsoil calculator
- Measure the area, or split an irregular yard into rectangles and circles and add them up.
- Enter the depth you want after the soil settles. Keep the 10% extra, because loose soil compacts once it is watered and walked on.
- Choose the material. Fill dirt is for raising grade; topsoil is for anything you will plant in.
The formula
Cubic feet = area (sq ft) × depth (in) ÷ 12, and cubic yards = cubic feet ÷ 27. Weight uses Engineering ToolBox densities: about 80 lb per cubic foot for loam, 76 to 78 for loose fill dirt and 100 for dry clay. Divide pounds by 2,000 for tons.
Worked example: a 20 × 10 ft area, 4 inches deep
200 × 4 ÷ 12 = 66.7 cubic feet, or 2.47 cubic yards. With 10% extra you need about 2.7 cubic yards, roughly 2.9 tons of loam, or 37 bags of 2 cu ft.
Recommended depths
| Project | Depth | Source |
|---|---|---|
| New lawn | 4 to 6 in (settled) | Penn State Extension |
| Improving garden beds | 2 to 3 in, mixed into the top 6 to 8 in | Miracle-Gro product directions |
| Raised beds | Full inside depth of the bed | Measure your bed |
Topsoil for common projects
Loam at 80 lb per cubic foot, no extra added.
| Project | Cubic yards | Tons |
|---|---|---|
| 4 × 8 ft raised bed top-up, 3 in | 0.3 | 0.32 |
| 10 × 10 ft garden bed, 4 in | 1.23 | 1.33 |
| 20 × 30 ft lawn patch, 4 in | 7.41 | 8 |
| 1,000 sq ft new lawn, 6 in | 18.52 | 20 |