Box / room
Also: rectangular prism, bed, trench, room
V = L × W × H
L = length, W = width, H = height or depth.
Example: A new lawn area 30 × 20 ft with 4 in of topsoil: 30 × 20 × 0.333 = 200 cu ft = 7.41 cu yd, about 9 tons of moist topsoil.
Quick answer: cubic yards of topsoil = length × width (ft) × depth (in) ÷ 324. One cubic yard covers 81 sq ft at 4 in deep. A new lawn typically needs 4–6 in of settled topsoil.
How to calculate how much topsoil you need
- Measure the area in feet. Split odd shapes into rectangles and circles, or use “Area × depth” if you already know the square footage.
- Choose the depth in inches: the finished depth you want after the soil settles.
- Multiply length × width × (depth ÷ 12) to get cubic feet.
- Divide by 27 for cubic yards, the unit bulk topsoil is sold in.
- Add a settling allowance if you are building up to a finished depth.
Cubic yards = L (ft) × W (ft) × depth (in) ÷ 324
The 324 is 12 × 27: it turns inches into feet and cubic feet into cubic yards in one step.
A lawn area 30 × 20 ft, 4 in deep:
30 × 20 × 4 ÷ 324 = 7.41 cu yd. With a 10% settling allowance, order about 8.15 cu yd.
How far a yard of topsoil goes
| Depth | 1 cu yd covers | Bags of 1 cu ft per 100 sq ft |
|---|---|---|
| 1 in | 324 sq ft | 9 |
| 2 in | 162 sq ft | 17 |
| 4 in | 81 sq ft | 34 |
| 6 in | 54 sq ft | 50 |
| 8 in | 40.5 sq ft | 67 |
| 12 in | 27 sq ft | 100 |
How deep should topsoil be?
| Job | Depth | Source |
|---|---|---|
| New lawn (seed or sod) | At least 4–6 in, settled | Penn State Extension |
| Raised bed on a hard surface: greens, beans, cucumbers | At least 8 in | University of Maryland Extension |
| Raised bed on a hard surface: tomatoes, peppers, squash | 12–24 in | University of Maryland Extension |
| Existing garden bed | Mix 2–4 in of compost into the top 4 in | University of Maryland Extension |
These are general guides. Local conditions, plants and your extension office’s advice come first.
How much a yard of topsoil weighs
Topsoil weight depends mostly on how wet it is and on its texture. The calculator uses two estimates, and you can enter your supplier’s own figure as a custom density:
| Topsoil | lb per cu ft | Per cu yd |
|---|---|---|
| Dry | 75 | about 2,000 lb (1.0 ton) |
| Moist (typical delivery) | 90 | about 2,400 lb (1.2 tons) |
How these figures were worked out: loam with a bulk density of 1.2 g/cm³ weighs 1.2 × 62.4 = 75 lb per cu ft dry. That is below the 1.40 g/cm³ ceiling the USDA NRCS bulk density guide gives for loam. The moist figure adds 20% water by weight. Real deliveries vary, so treat tons as an estimate and buy by the yard when you can.
Topsoil for different shapes
Use the shape closest to each area, add it to the project total and move on to the next one.
Area × depth
Also: square feet to cubic feet
V = A × d
A = area, d = depth or thickness.
Example: A 1,000 sq ft yard covered 4 in deep: 1,000 × 0.333 = 333 cu ft = 12.35 cu yd, about 15 tons moist.
Cylinder
Also: round hole, post hole, tank, planter
V = π × r² × h
r = radius (half the diameter), h = height.
Example: A round planting bed 6 ft across, filled 12 in deep: π × 3² × 1 = 28.3 cu ft = 1.05 cu yd.
Sloped slab
Also: ramp, uneven depth, tapered bed
V = L × W × (h₁ + h₂) ÷ 2
L = length, W = width, h₁ and h₂ = depth at each end.
Example: Leveling a low strip 40 × 10 ft that needs 6 in at one side and 2 in at the other: 40 × 10 × (0.5 + 0.167) ÷ 2 = 133 cu ft = 4.94 cu yd.
Worked examples
New lawn
A 1,000 sq ft back yard with 4 in of topsoil: 1,000 × 4 ÷ 324 = 12.35 cu yd, about 15 tons moist. Two or three truckloads, depending on the truck.
Raised bed
An 8 × 4 ft raised bed filled 10 in deep: 8 × 4 × 10 ÷ 12 = 26.7 cu ft = 0.99 cu yd. As bags, that is 27 bags of 1 cu ft or 36 bags of 0.75 cu ft. For a 1:1 topsoil and compost mix, buy about half of each.
Top-dressing a lawn
Spreading ¼ in over 2,000 sq ft: 2,000 × 0.25 ÷ 324 = 1.54 cu yd.
Tips
- Ask for screened topsoil for lawns and beds; it has fewer stones and clods.
- Check where the truck can dump. A load of topsoil is heavy; keep it off septic fields and soft lawns.
- Mulching the beds afterwards? Use the mulch calculator. For a gravel path next to the lawn, try the gravel calculator.
Frequently asked questions
How much topsoil do I need?
Multiply length × width in feet by the depth in inches ÷ 12 to get cubic feet, then divide by 27 for cubic yards. A 30 × 20 ft area at 4 in deep needs 200 cu ft, which is 7.41 cubic yards.
How much area does a yard of topsoil cover?
One cubic yard covers 324 sq ft at 1 in deep, 162 sq ft at 2 in, 81 sq ft at 4 in and 54 sq ft at 6 in.
How many bags of topsoil make a yard?
A cubic yard is 27 cu ft: that is 36 bags of 0.75 cu ft, 27 bags of 1 cu ft or 18 bags of 1.5 cu ft. Check the volume printed on the bag, not just the weight.
How much does a yard of topsoil weigh?
It depends mostly on moisture. As an estimate, dry loamy topsoil is about 2,000 lb (1 US ton) per cubic yard and moist topsoil about 2,400 lb (1.2 tons). Ask your supplier for their figure if weight matters for your truck or a ton price.
How deep should topsoil be for a new lawn?
Penn State Extension says a minimum of 4 to 6 inches of good-quality topsoil, measured after it is firmed or settled, is typically needed for new turf. Spread loose soil a little deeper so it settles to that depth.
How deep should soil be in a raised bed?
University of Maryland Extension suggests at least 8 in for leafy greens, beans and cucumbers and 12–24 in for peppers, tomatoes and squash when the bed sits on a hard surface. Beds on open ground can be shallower because roots grow into the soil below.
Should I mix compost with topsoil?
Often, yes. For raised beds over compacted clay, University of Maryland Extension suggests a mix of compost and purchased topsoil in a 1:2 or 1:1 ratio. Use the calculator for the total volume, then split it by your ratio.
Why add a settling allowance?
Loose topsoil settles as it is rolled, watered and walked on. If you need a finished depth, choose an allowance so you order enough loose soil. How much it settles depends on the soil and how it is placed, so ask your supplier.
Is topsoil cheaper by the yard or in bags?
For more than about a cubic yard, bulk topsoil delivered by the yard is usually much cheaper per cubic foot than bags. Enter both prices in the calculator to compare for your project.
Is this topsoil calculator free to use online?
Yes. The CalcWall Topsoil Calculator is completely free and works online in any browser, on a phone, tablet or computer. There is nothing to download and no account to create, and the math runs right in your browser, so results appear as you type.