To find how much topsoil you need, multiply the area in square feet by the depth in inches and divide by 324. The answer is in cubic yards. For example, 1,000 sq ft at 4 inches deep is 1,000 × 4 ÷ 324 = about 12.35 cubic yards. How deep to spread it depends on the job. Penn State Extension says a new lawn typically needs a minimum of 4 to 6 inches (firmed or settled depth) of good-quality topsoil. For topdressing an existing lawn, University of Wisconsin Extension says to spread no more than ¼ to ½ inch. Raised vegetable beds are usually filled 8 to 12 inches deep or more.
To skip the math, enter your area and depth in the Topsoil Calculator. It gives cubic yards, tons and bags.
The formula
- Cubic yards = area (sq ft) × depth (in) ÷ 324
- Cubic feet = area (sq ft) × depth (in) ÷ 12
- Cubic yards = cubic feet ÷ 27
The 324 comes from 27 cubic feet in a cubic yard times 12 inches in a foot. For a circle use π × (diameter ÷ 2)² for the area, and for an irregular area split it into rectangles and circles and add them together. The area formulas are the same ones explained in square feet to cubic yards.
How deep should topsoil be?
| Project | Typical depth | Source |
|---|---|---|
| New lawn (seed or sod) | 4 to 6 inches, firmed or settled | Penn State Extension |
| Topdressing an existing lawn | ¼ to ½ inch at most | University of Wisconsin Extension |
| Raised bed over poor or compacted soil | At least 8 inches of compost-topsoil mix | University of Maryland Extension |
| Raised bed on a hard surface: leafy greens, beans, cucumbers | At least 8 inches deep | University of Maryland Extension |
| Raised bed on a hard surface: peppers, tomatoes, squash | 12 to 24 inches deep | University of Maryland Extension |
| Framed raised bed box | At least 6 to 12 inches high | Utah State University Extension |
These are starting points, so check your own site and plants. Measure the depth of the good soil you already have and order only the difference.
How much one cubic yard covers
| Depth | Cubic yards per 1,000 sq ft | Area covered by 1 cubic yard (sq ft) |
|---|---|---|
| ¼ inch | 0.77 | 1,296 |
| ½ inch | 1.54 | 648 |
| 1 inch | 3.09 | 324 |
| 2 inches | 6.17 | 162 |
| 3 inches | 9.26 | 108 |
| 4 inches | 12.35 | 81 |
| 6 inches | 18.52 | 54 |
| 8 inches | 24.69 | 40.5 |
| 12 inches | 37.04 | 27 |
Multiply the cubic yards per 1,000 sq ft by your area divided by 1,000. For 2,500 sq ft at 4 inches, that is 12.35 × 2.5 = 30.86 cubic yards.
Topsoil for a new lawn
Penn State Extension says a good-quality turf typically needs a minimum of 4 to 6 inches of topsoil, measured as firmed or settled depth, and that it should be spread evenly to the grade marked on stakes. It also suggests working a 1 to 2 inch layer of peat or compost 4 to 6 inches into the soil, and tilling at least 4 inches deep. Sod and seed need the same bed, which is why the depth does not change between them.
| Lawn area | Cubic yards at 4 inches | Cubic yards at 6 inches |
|---|---|---|
| 500 sq ft | 6.17 | 9.26 |
| 1,000 sq ft | 12.35 | 18.52 |
| 2,500 sq ft | 30.86 | 46.3 |
| 5,000 sq ft | 61.73 | 92.59 |
| 10,000 sq ft | 123.46 | 185.19 |
Settled depth matters. Loose topsoil settles after it is spread and watered, so order a little extra. The calculator has an optional extra selector (5%, 10% or 15%) for this, and it defaults to 0%.
Topdressing and filling low spots in an existing lawn
Do not bury a lawn. University of Wisconsin Extension describes topdressing as a thin layer of soil, usually no more than ¼ to ½ inch, and warns that at least half of the leaf height should stay visible or the turfgrass may be killed by lack of sunlight. A few cubic yards go a long way: 5,000 sq ft at ¼ inch is 5,000 × 0.25 ÷ 324 = about 3.86 cubic yards. The same publication says large dips or swales can be corrected by adding soil to the area with a shovel. For a deeper hollow, many people lift the turf, fill the hole and replace the turf, rather than burying the grass.
Topsoil for raised beds and gardens
University of Maryland Extension recommends a minimum of 8 inches of a compost-topsoil or soilless media-compost mix over poor or compacted soil, and beds at least 8 inches deep for leafy greens, beans and cucumbers or 12 to 24 inches for peppers, tomatoes and squash when they sit on a hard surface. Utah State University Extension advises that a framed bed shallower than 12 inches be built without a bottom so roots can reach the soil below. A bed full of plain topsoil is not usually the goal, so ask for a blend with compost.
| Bed size | 8 inches deep | 12 inches deep |
|---|---|---|
| 4 × 4 ft | 10.7 cu ft (0.4 cu yd) | 16 cu ft (0.59 cu yd) |
| 3 × 6 ft | 12 cu ft (0.44 cu yd) | 18 cu ft (0.67 cu yd) |
| 4 × 8 ft | 21.3 cu ft (0.79 cu yd) | 32 cu ft (1.19 cu yd) |
| 4 × 12 ft | 32 cu ft (1.19 cu yd) | 48 cu ft (1.78 cu yd) |
Cubic feet also gives you the bag count: a 4 × 8 ft bed at 12 inches takes 32 cubic feet, which is 32 bags of 1 cu ft or 16 bags of 2 cu ft.
From cubic yards to tons and bags
Bulk topsoil is sold by the cubic yard or by the ton. Typical topsoil weighs about 1.1 tons per cubic yard, and wet soil can weigh much more, so the order you place by weight is not the same number as by volume. See how much does a yard of topsoil weigh for the ranges. For bags, divide 27 by the bag size in cubic feet: 27 bags of 1 cu ft, 36 bags of 0.75 cu ft or 13.5 bags of 2 cu ft per cubic yard.
Worked examples
- New 2,000 sq ft lawn at 4 inches: 2,000 × 4 ÷ 324 = 24.69 cubic yards, or about 27 tons at 1.1 tons per yard.
- Topdressing 5,000 sq ft at ¼ inch: 5,000 × 0.25 ÷ 324 = 3.86 cubic yards.
- Filling a 10 × 10 ft hollow 2 inches deep: 100 × 2 ÷ 324 = 0.62 cubic yards.
- Raised bed 4 × 8 ft, 12 inches deep: 32 cubic feet, or 1.19 cubic yards.
Common questions
How much topsoil do I need for 1,000 square feet?
At 4 inches it is about 12.35 cubic yards, at 6 inches about 18.52, at 2 inches about 6.17 and at ¼ inch (topdressing) about 0.77.
How many cubic yards of topsoil per acre?
An acre is 43,560 sq ft, so multiply the 1,000 sq ft figure by 43.56. At 4 inches that is about 538 cubic yards.
Can I spread topsoil over existing grass?
Only in a thin layer. University of Wisconsin Extension limits topdressing to about ¼ to ½ inch so the grass is not smothered. For a thicker layer, the grass is usually removed first.
How much extra should I order?
Loose topsoil settles once it is spread and watered. Penn State Extension measures the 4 to 6 inch minimum as firmed or settled depth, so a small allowance on top of your calculation is sensible. Use the extra selector in the calculator.
Bottom line
Area (sq ft) × depth (in) ÷ 324 gives cubic yards. Use 4 to 6 inches for a new lawn, no more than ¼ to ½ inch for topdressing, and 8 inches or more for raised beds. To turn your measurements into cubic yards, tons and bags, use the Topsoil Calculator. Planning the lawn itself? See the Grass Seed Calculator and how much grass seed do I need, or the Sod Calculator and how to lay sod.