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Topsoil Calculator: Soil for Lawns and Garden Beds
Work out how much topsoil, garden soil or compost you need to fill a raised bed, level a lawn or start a new garden, in cubic yards, bags and tons.
How much soil for a raised bed?
Multiply length × width × depth in feet to get cubic feet. A 4 × 8 ft raised bed 12 inches deep holds 32 cu ft, which is 1.19 cubic yards. Bagged garden soil usually comes in 1 to 1.5 cu ft bags, so the same bed needs 22 to 32 bags; a single yard of bulk soil is often cheaper.
Soil settles by 10 to 20% after watering, so fill raised beds slightly above the top and top up after the first few weeks.
How deep should topsoil be?
- New lawn: 4 to 6 inches of topsoil on top of loosened ground.
- Top-dressing an existing lawn: ¼ to ½ inch, spread thin enough that the grass shows through.
- Vegetable garden or raised bed: 8 to 12 inches; deeper for root crops.
- Flower beds: 6 to 8 inches.
Topsoil vs garden soil vs compost
Topsoil is screened native soil, good for filling and leveling. Garden soil or raised bed mix is topsoil blended with compost or other organic matter for planting. Compost is pure organic matter, usually mixed in at 1 to 3 inches rather than used alone. A cubic yard of topsoil weighs about a ton, so check your truck's payload before hauling it yourself.
Frequently asked questions
How much soil do I need for a 4x8 raised bed?
A 4 × 8 ft bed 12 in deep needs 32 cu ft, which is about 1.2 cubic yards or 22 bags of 1.5 cu ft.
How much does a yard of topsoil weigh?
About 1 to 1.2 tons when dry, and more when wet.