How to calculate topsoil
- Measure the area in feet — lawn, bed or raised bed.
- Pick the depth for the job (see below). New lawns and vegetable beds need far more than top-dressing.
- Convert to cubic yards: area × depth in inches ÷ 324.
- Add 10–20% because loose topsoil settles after it is watered and rolled.
Topsoil formula
Worked example: soil for a new lawn
A 25 × 20 ft lawn area (500 sq ft) prepared with 4 in of topsoil needs 500 × 4 ÷ 324 = 6.17 cubic yards. With 15% for settling, order about 7.1 cubic yards — around 7.8 tons of screened topsoil.
Worked example: a raised bed
A raised bed 8 ft × 4 ft and 12 in deep holds 8 × 4 × 12 ÷ 324 = 1.19 cubic yards, or about 43 bags of 0.75 cu ft. For deep beds, bulk soil is usually far cheaper than bags.
How deep should topsoil be?
| Project | Typical depth |
|---|---|
| Top-dressing an existing lawn | ¼–½ in |
| Overseeding bare patches | ½–1 in |
| New lawn from seed or sod | 4–6 in |
| Flower beds | 6–8 in |
| Vegetable garden | 8–12 in |
| Raised beds | Full bed depth (often 10–12 in) |
Topsoil coverage chart
| Depth | Area covered by 1 cubic yard | 0.75 cu ft bags per 100 sq ft |
|---|---|---|
| ½ in | 648 sq ft | 6 |
| 1 in | 324 sq ft | 12 |
| 2 in | 162 sq ft | 23 |
| 4 in | 81 sq ft | 45 |
| 6 in | 54 sq ft | 67 |
Choosing good topsoil
- Screened topsoil has had rocks, roots and clods removed and spreads far more easily.
- Look for dark, crumbly loam that smells earthy. Avoid soil that is mostly sticky clay or pale sand.
- Ask whether it has been tested and whether it is free of weed seeds and debris.
- For beds, a topsoil–compost blend adds organic matter; for structural fill, use fill dirt instead.
- Your local cooperative extension service can test soil pH and nutrients for a small fee.
Spreading tips
- Loosen the existing ground a few inches first so the new soil bonds to it rather than forming a layer.
- Spread in 2–3 in passes with a rake, then roll lightly and water to settle it before seeding.
- Keep finished grade sloping away from the house and below siding.
- One cubic yard of topsoil weighs about a ton — too much for most pickup beds in one trip.
Frequently asked questions
How much topsoil do I need?
Multiply length × width in feet by depth in inches, divide by 324, then add 10–20% for settling. A 500 sq ft lawn at 4 in needs about 7.1 cubic yards with 15% extra.
How much area does a yard of topsoil cover?
One cubic yard covers 324 sq ft at 1 in deep, 162 sq ft at 2 in, 81 sq ft at 4 in, and 54 sq ft at 6 in.
How much does a cubic yard of topsoil weigh?
About 2,000–2,400 lb (1–1.2 tons), depending on moisture. Wet soil can weigh more.
How many bags of topsoil are in a yard?
A cubic yard is 27 cu ft: 36 bags of 0.75 cu ft or 27 bags of 1 cu ft.
How much topsoil do I need for new sod?
Most guides recommend 4–6 in of good topsoil under new sod or seed — about 1.2–1.9 cubic yards per 100 sq ft.
Sources & standards
This calculator's formulas and default values are based on the following codes, standards and published data. Codes are adopted and amended locally, so check with your building department for permitted work. See how we build and check our calculators.
- University cooperative extension lawn establishment guidance (for example, extension turfgrass publications recommending 4–6 in of topsoil for new lawns).
- USDA NRCS soil texture and bulk density references.
- Retail bag sizes: 0.75 ft³ and 1 ft³; 1 yd³ = 27 ft³.