Material planning guide
How Much Topsoil Do I Need? Depth, Area and Order Size
For a uniform layer, multiply length by width by depth. With feet for length and width and inches for depth, divide their product by 324 to obtain cubic yards.
Reviewed September 6, 2026Convert area and depth into volume
A 30 × 20 ft area is 600 ft². A new 4-inch layer contains 200 ft³, or 7.407 yd³ before allowance. A 10% purchase allowance gives 8.148 yd³; a supplier using half-yard increments would quote 8.5 yd³.
600 ft² at different added depths
Before allowance and delivery rounding.
| Added depth | Measured yd³ |
|---|---|
| 1 in | 1.852 |
| 2 in | 3.704 |
| 4 in | 7.407 |
| 6 in | 11.111 |
New layer versus finished ground level
The required depth is the thickness of new material. If you are correcting a slope, the difference between old and new levels varies across the area. Split the area into zones or obtain a site takeoff rather than assuming the maximum depth everywhere.
Ask what the supplier is actually selling
Confirm whether the quote is in cubic yards, bags, or weight and what the material specification includes. Screening, moisture, and soil composition affect the delivered product; a volume calculator cannot verify suitability. Soil testing can help determine whether topsoil or an amendment is needed.
- Request the delivery increment and minimum order.
- Keep any settlement allowance explicit.
- Record whether the quote includes delivery and spreading.
Sources and product references
- University of Minnesota Extension — soil testing
Soil and nutrient needs should be assessed before choosing amendments.
- NIST — SI units: volume
Unit relationships; supplier product coverage and prices remain separate inputs.