How Much Topsoil Do I Need?
The exact method landscapers use to estimate topsoil — convert area and depth to cubic yards, add for settling, and read the weight in tons. Includes a worked example and a quick reference table.
To find how much topsoil you need, multiply length × width × depth in feet to get cubic feet, then divide by 27 to get cubic yards. Add about 10% for settling, and multiply cubic yards by roughly 1.10 to estimate tons of screened topsoil. A 30 ft × 20 ft garden filled 6 inches deep works out to 300 cubic feet, or 11.11 cubic yards — about 12.22 cubic yards with settling, and close to 13.44 tons.
Topsoil is sold by volume, but almost nobody thinks in cubic yards — you think in beds, lawns, and truckloads. That gap is where projects go wrong: order too little and you stop short of final grade with the delivery truck already gone; order too much and you are paying to haul away a pile you did not need. The fix is a short piece of arithmetic that turns the area you can see into the cubic yards a supplier actually sells. This guide walks through that math step by step, with a worked example and a reference table you can copy.
If you would rather skip the pencil work, the topsoil calculator runs every step below and returns cubic yards, tons, and bag counts instantly. Understanding the method still pays off, because it lets you sanity-check any quote a landscaper gives you.
The three numbers that decide everything
Every topsoil estimate comes down to three inputs:
- Area — the square footage you are covering.
- Depth — how deep you are filling, in inches.
- Settling — the extra you add so the finished grade holds.
Weight in tons is a fourth number, but it is derived from the first three plus the soil’s density. Nail area and depth and the rest is multiplication and division.
Step 1: Find the area
For a rectangular bed or lawn, multiply the two sides:
Area (sq ft) = length × width
A 30 ft × 20 ft garden is 30 × 20 = 600 sq ft. Round beds use π × (diameter ÷ 2)² instead — an 8 ft round bed is about 50 sq ft. Odd shapes are easiest to break into rectangles and add together.
Step 2: Convert depth and get cubic feet
Here is the step people trip over: depth is measured in inches, but area is in feet, so you have to put them in the same unit before multiplying. Divide inches by 12 to get feet, then:
Volume (cu ft) = area × (depth ÷ 12)
Six inches is 6 ÷ 12 = 0.5 ft, so our 600 sq ft garden holds 600 × 0.5 = 300 cubic feet. Choosing the right depth is its own decision — a lawn topdressing wants far less than a raised bed. The topsoil depth guide gives target depths for every common use.
Step 3: Divide by 27 for cubic yards
A cubic yard is 3 ft × 3 ft × 3 ft, which is 27 cubic feet. Since bulk topsoil is priced and delivered by the cubic yard, that is the number you actually order:
Cubic yards = cubic feet ÷ 27
300 ÷ 27 = 11.11 cubic yards. That is the raw volume of the hole you are filling.
Step 4: Add for settling
Fresh topsoil is fluffy. After it is spread, watered, and given a few weeks, it compacts and drops 10–20%. If you order only the raw volume, your finished grade ends up low. Add about 10% to reach and hold the height you want:
Order = cubic yards × 1.10
11.11 × 1.10 = 12.22 cubic yards to buy. This is exactly what the calculator’s default settling factor does.
Step 5: Convert to tons (optional)
Many suppliers quote by weight. Multiply cubic yards by the material’s density in tons per cubic yard:
Tons = cubic yards × density
Screened topsoil is about 1.10 tons per cubic yard, so 12.22 × 1.10 ≈ 13.44 tons. Moist soil is heavier at roughly 1.35, and airy compost is lighter near 1.00 — the density you use depends on what you are buying, which is exactly why topsoil vs garden soil vs compost matters before you place an order.
Worked example, start to finish
A 30 ft × 20 ft vegetable garden, filled 6 inches deep with screened topsoil:
- Area:
30 × 20 = 600 sq ft - Volume:
600 × (6 ÷ 12) = 300 cu ft - Cubic yards:
300 ÷ 27 = 11.11 cu yd - With 10% settling:
11.11 × 1.10 = 12.22 cu yd - Weight:
12.22 × 1.10 ≈ 13.44 tons
So you order about 12.25 cubic yards, or roughly 13.5 tons if the supplier sells by weight. Punch the same numbers into the topsoil calculator and you get 12.22 cubic yards and 13.44 tons — identical, because it runs the exact steps above.
Quick reference: cubic yards by area and depth
These are raw cubic yards before settling; add roughly 10% to reach final grade. Confirm any figure with the topsoil calculator.
| Area | 2 in deep | 4 in deep | 6 in deep | 12 in deep |
|---|---|---|---|---|
| 100 sq ft | 0.62 cu yd | 1.23 cu yd | 1.85 cu yd | 3.70 cu yd |
| 200 sq ft | 1.23 cu yd | 2.47 cu yd | 3.70 cu yd | 7.41 cu yd |
| 400 sq ft | 2.47 cu yd | 4.94 cu yd | 7.41 cu yd | 14.81 cu yd |
| 800 sq ft | 4.94 cu yd | 9.88 cu yd | 14.81 cu yd | 29.63 cu yd |
| 1,000 sq ft | 6.17 cu yd | 12.35 cu yd | 18.52 cu yd | 37.04 cu yd |
Bulk or bags?
Small jobs — a single raised bed or a couple of planters — are usually cheapest in bags. A common bag holds 0.75 cubic feet (about 40 lb), and it takes 36 of them to make a cubic yard. Past roughly one cubic yard, that is a lot of bags to haul and open, so a bulk delivery wins even after the delivery fee. The calculator shows both counts so you can compare at your exact size.
Where estimates go wrong
The three most common mistakes are forgetting to convert depth from inches to feet (which throws the volume off by a factor of 12), skipping the settling factor and finishing low, and using the wrong density so the tonnage — and the bill — comes in short. Get the depth right for your use in the topsoil depth guide, match the material to the job in topsoil vs garden soil vs compost, and let the topsoil calculator handle the arithmetic so none of those slip through.