How the topsoil calculator works
The calculator does the same sums a landscape supplier does on the phone. Here they are with the default numbers, a 20 × 10 ft area spread 4 inches deep:
- Area. Length × width for a rectangle, or 3.14 × radius² for a circle. 20 × 10 ft = 200 square feet.
- Volume. Area × depth in feet. Four inches is 4 ÷ 12 = 0.333 ft, so 200 × 0.333 = 66.7 cubic feet.
- Cubic yards. Cubic feet ÷ 27. 66.7 ÷ 27 = 2.47 cubic yards.
- Extra for settling. Add 10%: 66.7 × 1.1 = 73.3 cubic feet, or 2.72 cubic yards. Most yards sell in half or whole yards, so you would order 3.
cubic yards = length (ft) × width (ft) × depth (in) ÷ 12 ÷ 27
From there the card works out the rest. At 1 to 1.4 tons per cubic yard, 2.72 yards weighs about 2.7 to 3.8 tons, and the middle figure of 3.26 tons is what it shows on the “Tons, about” line. In bags, 73.3 cubic feet is 74 bags of 1 cubic foot, 98 bags of 0.75 cubic feet, 49 bags of 1.5 cubic feet or 37 bags of 2 cubic feet. Bag counts always round up.
Filling raised beds instead? Switch the calculator to Raised beds, enter the inside length, width and soil depth, and the number of beds. It also handles round galvanized ring beds. The raised bed soil calculator explains that mode in more detail.
Have an odd-shaped yard? Split it into rectangles and circles, run each one, and add the cubic yards together. The guide to how much topsoil you need works through an L-shaped area, a triangle and uneven ground.
How deep should topsoil be?
The right depth depends on what will grow in it. These are common starting points; your local extension service or supplier may suggest something different for your soil.
| Job | Typical topsoil depth | Notes |
|---|---|---|
| New lawn on bare or scraped ground | 4–6 in | See topsoil for a lawn. |
| Top dressing an existing lawn | ⅛–¼ in | Thin enough that the grass shows through. See the top dressing calculator. |
| Filling low spots in a lawn | up to about ½ in at a time | Add more after the grass grows back through. |
| New flower or vegetable bed on poor ground | 6–8 in | Often a garden soil blend rather than plain topsoil. |
| Freshening an existing bed | 1–3 in | Compost is often the better choice: see the compost calculator. |
| Raised bed | the full soil depth | Usually a mix. See the raised bed soil mix calculator. |
Coverage of one cubic yard of topsoil
A cubic yard is 27 cubic feet, a 3 × 3 × 3 ft cube. Spread out, it covers:
| Depth | Square feet covered by 1 cubic yard |
|---|---|
| 1 inch | 324 |
| 2 inches | 162 |
| 3 inches | 108 |
| 4 inches | 81 |
| 6 inches | 54 |
| 8 inches | 40.5 |
| 12 inches | 27 |
The topsoil coverage calculator works the other way round: tell it how many yards, tons or bags you have and it gives the square feet.
Cubic yards per 1,000 square feet
For bigger jobs it is easier to think in thousands of square feet. Multiply these figures by your area in thousands (2,500 sq ft = 2.5).
| Depth | Cubic feet per 1,000 sq ft | Cubic yards per 1,000 sq ft |
|---|---|---|
| ¼ inch | 20.8 | 0.77 |
| 1 inch | 83.3 | 3.09 |
| 2 inches | 166.7 | 6.17 |
| 3 inches | 250 | 9.26 |
| 4 inches | 333.3 | 12.35 |
| 6 inches | 500 | 18.52 |
Yards, tons or bags: how topsoil is sold
- By the cubic yard. Most landscape supply yards price bulk topsoil per yard and deliver by dump truck. This is the number the calculator leads with.
- By the ton. Some quarries and haulers sell by weight. Because a yard of topsoil weighs about 1 to 1.4 tons, a ton is a little less than a yard. Ask the supplier what their soil weighs per yard and use that. The page on how much a yard of topsoil weighs has a conversion table.
- By the bag. Garden centers sell topsoil in bags, usually 0.75 to 2 cubic feet. Bags are handy for small jobs and for places a truck can’t reach. For anything over a yard or two, compare the bag price against a delivered yard. The bags of soil calculator and the topsoil cost guide show how.
The weights here are typical ranges for loose topsoil. Soil straight from a wet stockpile can sit at the heavy end or beyond. If your supplier gives you their own weight per yard, use it, and confirm any quantity with them before you order.
Questions gardeners ask
- How do I calculate how much topsoil I need?
- Multiply length by width in feet to get square feet. Multiply by the depth in inches divided by 12 to get cubic feet. Divide by 27 to get cubic yards. A 20 × 10 ft area at 4 inches is 200 × 0.333 = 66.7 cubic feet, or about 2.5 cubic yards.
- How many square feet does a yard of topsoil cover?
- One cubic yard covers about 324 square feet at 1 inch deep, 162 at 2 inches, 108 at 3 inches, 81 at 4 inches and 54 at 6 inches.
- How much does a cubic yard of topsoil weigh?
- About 1 to 1.4 tons (2,000 to 2,800 lb), depending mostly on how wet it is. The calculator uses the middle, about 1.2 tons, and shows the range.
- How many bags of topsoil make a cubic yard?
- A cubic yard is 27 cubic feet, so it takes 36 bags of 0.75 cubic feet, 27 bags of 1 cubic foot, 18 bags of 1.5 cubic feet or 13.5 bags of 2 cubic feet.
- How much extra topsoil should I order?
- About 10 percent is a sensible default for flat areas. Loose soil settles once it is raked and watered, so deep beds and fills often need 15 to 20 percent more, or a top-up later.