Topsoil calculator

How the calculator works

1. Area of the shape in square feet. For an odd-shaped yard, split it into rectangles and triangles and run each one, or total the area first with the square footage calculator.
2. Volume: area × depth in inches ÷ 12 = cubic feet; ÷ 27 = cubic yards. Bulk topsoil is sold by the cubic yard.
3. Bags: cubic feet ÷ the bag size printed on the bag, rounded up.
4. Weight: cubic yards × weight per cubic yard. This matters for a pickup's payload or a trailer. The default 1.10 tons per cubic yard is one supplier's published figure for dry screened topsoil, about 2,200 lb per yard. Damp soil is heavier.

Worked example

2 in of topsoil over a 20 × 15 ft area before seeding:

• Area: 20 × 15 = 300 ft²
• Volume: 300 × 2 ÷ 12 = 50 ft³, which is 1.85 yd³
• Plus 5%: 52.5 ft³ = 1.94 yd³
• In 0.75 ft³ bags: 52.5 ÷ 0.75 = 70 bags (53 one-cubic-foot bags)
• Weight: about 1.94 × 1.10 ≈ 2.1 tons, over 4,000 lb. Check the payload rating on your truck's door-jamb sticker before you haul it yourself.

How deep to spread it

• Over existing grass, go thin. Clemson's Home & Garden Information Center advises topdressing an established lawn no more than about ¼ to ½ in at a time, so the grass can grow through. Fill deeper dips in stages, or lift the sod, fill under it and relay it.
• Bare ground, new lawn or new bed: spread the depth you need, then rake and lightly firm it. Loose soil settles, which is what the extra allowance covers.
• Near the house, keep soil below siding and away from wood, and slope it away from the foundation. The yard-leveling guide explains the 6-inch-in-10-feet rule.

Assumptions

• Bag sizes vary, so use the number printed on yours. A “40 lb bag” is a weight, not a volume. If the bag only lists weight, the calculator can't convert it reliably.
• “Topsoil”, “garden soil” and “fill dirt” are different products. Fill dirt is for raising grade. Topsoil and garden soil are what grass and plants grow in.