How much topsoil do you need?
A 20 × 30 ft lawn at 6 inches deep needs 300 cubic feet of topsoil, which is 11.11 cubic yards, or 12.22 tons at 1.10 tons per cubic yard, and 400 bags of 0.75 cubic feet.
Topsoil orders go wrong when people buy by the bag for a whole yard, or when they spread a 1 inch “dusting” and expect a new lawn to take. Start from area and depth, then decide bags versus a truck.
- Enter length and width of the bed or lawn in feet.
- Enter the finished depth in inches. Two to three inches over poor soil can revive turf. Six inches is a serious new bed.
- Keep the default 1.10 tons per cubic yard for loose soil, or switch to compacted or wet if that matches what the yard sells.
- Read cubic yards for a bulk delivery. Use the bag line for 0.75 and 1 cubic foot bags.
- Type your local price per yard or per ton under Estimate cost.
Cubic feet = square feet × (inches ÷ 12). Cubic yards = cubic feet ÷ 27. Tons = cubic yards × 1.10 unless you change density. Bags of 0.75 cubic feet = cubic feet ÷ 0.75, rounded up.
How to calculate how much topsoil I need
Multiply square feet by the depth in feet, then divide by 27. A 20 × 30 ft lawn at 6 inches is 600 × 0.5 ÷ 27 = 11.11 cubic yards. At 1.10 tons per cubic yard that is 12.22 tons, or 400 bags of 0.75 cubic feet.
Worked example: 20 × 30 lawn at 6 inches
Worked example
20 ft by 30 ft, 6 inches of loose topsoil at 1.10 tons per cubic yard.
20 × 30 = 600 square feet. Six inches is 0.5 feet. 600 × 0.5 = 300 cubic feet. 300 ÷ 27 = 11.11 cubic yards. (300 ÷ 27) × 1.10 = 12.22 tons. Bags: 300 ÷ 0.75 = 400 bags of 0.75 cubic feet, or 300 bags of 1 cubic foot.
That is the default result on this page. The same 600 square feet at 3 inches is half the volume: 150 cubic feet, 5.56 yards, 6.11 tons, 200 bags of 0.75 cubic feet.
Eleven yards is a tandem-axle dump, not a car trunk load. If you only need to scratch in a half inch of compost, this is the wrong depth and the wrong product.
Topsoil coverage per cubic yard and per bag
| Depth | Area one cubic yard covers | 0.75 cu ft bags per 100 sq ft | 1 cu ft bags per 100 sq ft |
|---|---|---|---|
| 2 in | 162 sq ft | 23 | 17 |
| 3 in | 108 sq ft | 34 | 25 |
| 4 in | 81 sq ft | 45 | 34 |
| 6 in | 54 sq ft | 67 | 50 |
| 8 in | 40.5 sq ft | 89 | 67 |
Questions
How do I calculate how much topsoil I need?
How many yards of topsoil for a 20 × 30 lawn?
How much area does a cubic yard of topsoil cover?
How many bags of topsoil equal a cubic yard?
How deep should topsoil be for a new lawn?
How much does a yard of topsoil weigh?
Should I buy bags or a bulk delivery?
What is the difference between topsoil and fill dirt?
Written by The BuildMath team. Formulas tested against worked examples. Updated October 21, 2026.