Cubic feet = area (sq ft) × depth (in ÷ 12). Cubic yards = cubic feet ÷ 27, with waste applied first. Optional bags = ceiling(cubic feet ÷ bag size).
How topsoil volume is figured
Topsoil is sold by volume, not by the area you see from the street. Measure every patch you plan to cover—new lawn rectangles, garden expansions, low spots in the yard, or the footprint of a raised bed—then multiply by how deep the layer should be. Depth is always converted to feet: 4 inches is 4 ÷ 12 ≈ 0.33 feet.
For a rectangle, area is length × width in feet. Odd shapes can be split into smaller rectangles and added, or you can pace off average length and width. Once you have square feet, volume in cubic feet is area × depth in feet. There are 27 cubic feet in one cubic yard, which is how bulk suppliers price truck or dump delivery.
Fresh topsoil settles after rain and wheelbarrow traffic, and you lose a little on slopes. A small waste percentage keeps you from running short on the last pass. Five percent is a fair default; use ten percent on steep grades or when you are filling over rubble or old stump holes.
How deep should topsoil be?
½ inch topdress adds organic matter to an existing lawn without burying grass crowns—common after aeration. 2 inches helps level minor dips before sod or seed. 4 inches is a typical target when you are establishing a new lawn on subsoil or stripped construction fill. 6 inches suits raised beds and deep vegetable plots where roots need room; go deeper only if your design calls for it and retaining edges can hold the weight.
If you are only filling low spots, measure those patches separately rather than averaging depth over the whole lawn—you will order less and avoid building a “lawn bowl.” For sod installs, finish grade so the new turf sits flush with walks and driveways; use our sod calculator for pallet counts once the base is ready.
Worked example: 20 × 10 foot area, 4″ deep
Area = 20 × 10 = 200 sq ft. Depth = 4″ = 0.333 ft. Volume = 200 × 0.333 ≈ 66.7 cubic feet. With 5% waste, 66.7 × 1.05 ≈ 70 cu ft. Cubic yards = 70 ÷ 27 ≈ 2.59, so order 2.75 or 3 cubic yards of bulk topsoil (round up to what your supplier sells). Bagged topsoil at 1 cu ft per bag would be about 70 bags— workable for a tiny patch, impractical for a full lawn.
Quick FAQ
- Bulk or bags? Anything much over a cubic yard is usually cheaper and faster with bulk delivery. Bags make sense for topping one garden bed or filling a few holes.
- Topsoil vs garden mix? Volume math is identical. Blended mixes may be lighter per yard but still order by cubic yards using the same depth × area formula.
- Do I need a soil test? This page only estimates quantity. Heavy clay or construction fill may need amendments beyond volume alone.
- Mulch or sod next? For bark and wood-chip depth, see the mulch calculator. For turf pallets and rolls after grading, try the sod calculator.
About this tool
This is a browser-only topsoil quantity estimator for homeowners and small landscape jobs. Nothing you type is uploaded; the math runs on your device. It is part of a set of simple construction and planning helpers published by R7Global.
Questions or corrections: r7global@gmail.com