How to use the topsoil calculator
- Measure the area you want to cover. For raised beds, enter the inside length and width of the bed.
- Enter the depth. For raised beds, use the bed height minus any space you leave at the top.
- Keep a settling allowance. Topsoil is fluffy when delivered and settles as it is watered and walked on; 10% is a sensible default, 15–20% for raised beds.
- Choose bulk or bags. Bagged topsoil is usually 0.75 or 1 cu ft.
How much topsoil do I need?
- New lawn from seed or sod: 4–6 inches. University extension services commonly recommend at least 4 inches of good soil for turfgrass roots, and 6 inches where the existing soil is poor or compacted.
- Vegetable and flower beds: 6–8 inches worked into the existing soil.
- Raised beds: the full bed depth, often 10–12 inches, typically a topsoil and compost blend.
- Top-dressing a lawn: 1/4 to 1/2 inch at a time, so the grass is not smothered.
The topsoil formula
Cubic yards = area (sq ft) × depth (in) ÷ 12 × (1 + settling %) × (1 + waste %) ÷ 27
Tons = cubic yards × 27 × density (lb/ft³) ÷ 2,000
The Engineering ToolBox gives dry excavated loam at 1,249 kg/m³ (78 lb/ft³) and moist excavated earth at 1,442 kg/m³ (90 lb/ft³). So a cubic yard of topsoil weighs roughly 2,100 lb dry to 2,400 lb moist — about 1 to 1.2 tons. Topsoil is usually sold by the yard, so the weight mainly matters for hauling.
Worked example: new lawn
A back yard area of 30 × 20 ft needs 4 inches of topsoil, with 10% settling and 5% waste:
- Area: 30 × 20 = 600 sq ft
- Volume: 600 × 4 ÷ 12 = 200 cu ft → × 1.10 × 1.05 = 231 cu ft
- Cubic yards: 231 ÷ 27 = 8.56 yd³
- Weight dry: 231 × 78 = 18,018 lb ≈ 9.0 tons
- In 0.75 cu ft bags: 308 bags — bulk delivery is the only practical option here.
Worked example: raised bed
A 4 × 8 ft raised bed, 11 inches of soil, 15% settling: 32 × 11 ÷ 12 = 29.3 cu ft × 1.15 = 33.7 cu ft, or about 1.25 yd³. That is 45 bags of 0.75 cu ft or 34 bags of 1 cu ft.
Coverage per cubic yard
One cubic yard (27 cu ft) covers 324 sq ft at 1 inch, 81 sq ft at 4 inches, 65 sq ft at 5 inches and 54 sq ft at 6 inches, before settling.
Tips for buying topsoil
- Look at it first. Good topsoil is dark, crumbly and mostly free of rocks, roots and clods. Screened topsoil costs more but spreads far easier.
- Test your soil. A soil test from your county extension office tells you pH and nutrients so you can amend the new soil correctly.
- Blend, don't layer. Till the first couple of inches of new topsoil into the existing soil so water and roots move between them.
- Use fill dirt below. If you are raising grade by more than 6 inches, use cheaper fill for the bottom; see the dirt calculator.
Frequently asked questions
How much topsoil do I need for a lawn?
Plan 4–6 inches. For 1,000 sq ft at 4 inches you need about 12.3 cubic yards, plus around 10% for settling.
How many square feet does a yard of topsoil cover?
About 81 sq ft at 4 inches deep, 65 sq ft at 5 inches and 54 sq ft at 6 inches.
How much does a yard of topsoil weigh?
Roughly 2,100 lb dry to 2,400 lb moist, or about 1 to 1.2 tons per cubic yard.
How many bags of topsoil are in a yard?
36 bags of 0.75 cu ft, or 27 bags of 1 cu ft.
How much soil do I need for a 4x8 raised bed?
A 4 × 8 ft bed 12 inches deep holds 32 cubic feet, about 1.2 cubic yards; add 10–15% for settling.