Topsoil formula
Cubic yards = area × depth (in) ÷ 12 ÷ 27. Dry screened topsoil weighs roughly 1 to 1.3 tons per cubic yard; wet soil is heavier. Common retail bags are 0.75 or 1 cu ft.
Example: 500 sq ft at 4 in = 166.7 cu ft = 6.17 cu yd ≈ 6.8 tons at 1.1 t/yd. That's 223 bags of 0.75 cu ft—bulk delivery makes far more sense.
How deep?
- Top-dressing an existing lawn: 1/4–1/2 in
- New lawn over poor soil: 4–6 in
- Vegetable beds: 8–12 in (often a topsoil/compost blend)
Topsoil settles; order about 10–20% extra for fills deeper than a few inches.