How much topsoil do I need for a 20 × 10 ft area, 4 inches deep?
For the worked example (20 × 10 ft area, 4 in deep) the material list is Topsoil: 2.47 yd³ (calculated 2.469 yd³ before allowance, based on 4 in deep, no allowance). Quantities to buy are whole units rounded up from the calculated amounts. Enter your own measurements in the calculator above for your exact list.
How to use this calculator
- Measure the length and width of the area, or enter the area if you already know it.
- Enter the depth of topsoil you plan to spread.
- Pick the bag size on the bags you will buy (or enter a custom size).
- Use the cubic yards if you are ordering bulk delivery, or the bag count if you are buying bags.
- Copy, print or share the material list.
How this is calculated
- Volume (cu ft) = area (sq ft) × depth (ft), with depth in inches ÷ 12
- Cubic yards = cubic feet ÷ 27
- Bags = round up (cubic feet ÷ cubic feet per bag)
- Weight (optional) = cubic yards × the density your supplier gives you
Geometry is deterministic. Material coverage, density, installation waste and product yield can vary. We expose those assumptions so you can replace them with the values printed on the products you are actually buying. Treat every result as an estimate. Items on your list are labelled Calculated (straight from your measurements) or Estimated (depends on an assumption), and “Buy” quantities are whole units rounded up.
Sources
No third-party figure is built into this calculator. Quantities come from geometry and from the values you can see and edit under “Assumptions” below, each labelled by where it comes from.
Last reviewed: . See the methodology.
Assumptions
These starting values are used until you change them. They are typical, not universal. Check the label on the product you are buying.
| Assumption | Starting value | Where it comes from |
|---|---|---|
| Cubic feet in a cubic yard | 27 | Mathematical – 3 ft × 3 ft × 3 ft |
| Inches in a foot | 12 | Mathematical – Depth in inches ÷ 12 gives feet |
| Extra allowance | 0% | Common planning default |
| Custom bag size | You enter it | You enter it (product / supplier) |
Worked example
A 20 × 10 ft area covered 4 in deep, with 1.5 cu ft bags and no extra allowance:
- Topsoil: 2.47 yd³ (or 45 × 1.5 cu ft bags) · 4 in deep, no allowance
Common questions
How deep should topsoil be?
That depends on what you are growing and the soil underneath, so this tool does not recommend a depth. The 2, 4 and 6 inch buttons are only quick inputs.
Why is there no weight by default?
Topsoil density depends on the soil and how wet it is. We only show a weight if you enter the density your supplier gives you.
Does it add extra for settling?
No. The allowance starts at 0%. Add one if you want a cushion.
Guides
- How Much Topsoil Do I Need?Area and depth turned into cubic yards or bags of topsoil.
- How Much Topsoil for Lawn Leveling or New Grass?Thin layers over big areas: how small depths add up in cubic yards.
- How Much Mulch Do I Need?Bed area and depth turned into bags or cubic yards of mulch.
- How Mulch Depth Changes How Much You NeedSame bed at 2, 3 and 4 inches: how depth scales the quantity.
- How Much Soil Do I Need for a Raised Garden Bed?Length, width and fill depth, bed by bed, in yards and bags.