How to measure your area
For a simple rectangular lawn area, bed, or leveling job, measure the length and width in feet and enter them directly — the calculator multiplies them together to get square footage, then factors in depth to find volume.
If your area is irregular — a lawn with a curved edge, a bed that widens at one end — split it into two or more rectangles you can measure separately, work out the topsoil needed for each one, and add the results together. For a circular bed, use Area = π × r² (r is the radius, half the diameter), then enter that square footage as the length and 1 as the width, since length × width still gives the right area.
The formula and a worked example
The math behind this calculator, in three steps:
Cubic feet = Length ft × Width ft × (Depth in ÷ 12) × (1 + waste %)
Cubic yards = Cubic feet ÷ 27
Tons ≈ Cubic yards × 1.1
Dividing by 27 converts cubic feet to cubic yards, since a cubic yard is 3 ft × 3 ft × 3 ft = 27 cubic feet — the unit most suppliers use for pricing and delivery. The 1.1 multiplier for tons comes from screened topsoil weighing roughly 2,200 lb per cubic yard (2,200 ÷ 2,000 lb per ton = 1.1).
Worked example: a 20 ft × 10 ft area of lawn, filled 4 inches deep, with the default 5% waste allowance:
20 × 10 × (4 ÷ 12) = 66.7 cubic feet before waste
66.7 × 1.05 = 70 cubic feet
70 ÷ 27 = 2.59 cubic yards
2.59 × 1.1 ≈ 2.9 tons, or about 94 forty-pound bags
Without the waste allowance, that same area works out to about 2.47 cubic yards, or roughly 2.7 tons — the 5% buffer adds a little cushion for spillage and settling, which is usually cheaper than running short partway through the job.
How deep should topsoil be, job by job
The right depth depends heavily on what the topsoil is for. These are common starting points, not fixed rules — soil type and local conditions can shift them:
- Topdressing an existing lawn: a thin layer, about ¼–½ inch, is typically enough to level minor dips and feed the soil without smothering the grass.
- A new lawn from seed: 4–6 inches of topsoil tilled into the existing ground gives roots enough loose, fertile soil to establish properly.
- New garden beds: 6–12 inches is common for in-ground beds, and raised beds are usually filled to the height of the frame — often 8–12 inches or deeper.
If you're unsure, a local landscaper or garden center can confirm the right depth for your soil type, drainage, and what you're planting.
Why the weight of topsoil varies
This calculator assumes screened topsoil weighs about 2,200 lb per cubic yard (1.1 tons), which is a reasonable average — but real topsoil can weigh anywhere from around 2,000 lb per cubic yard when it's dry and loose to roughly 2,700 lb when it's moist, compacted, or has a high clay content. Sandy, well-drained topsoil tends to sit near the lighter end; heavier, clay-rich, or freshly watered soil sits near the top of that range.
Because the weight can swing by more than 30% depending on moisture and composition, treat the tons figure here as a planning estimate. If you're ordering by the ton from a supplier, ask them for the specific density of the topsoil they're delivering — that's the number that determines your final bill.
Bags vs bulk delivery
A cubic yard of topsoil works out to about 36 standard 40 lb bags (27 cubic feet ÷ 0.75 cubic feet per bag). Bagged topsoil is easy to transport in a car, easy to store, and ideal for container gardens, small beds, or patching a lawn.
For anything larger — a new lawn, a big garden bed, a significant leveling job — bulk delivery is almost always cheaper once you're past roughly a cubic yard. It also saves the physical effort of hauling dozens of individual bags. Many suppliers deliver in increments of a cubic yard or half-yard, so it's worth rounding your total up before you order.