How Much Topsoil Do I Need?

A 100-square-foot area topdressed 2 inches deep needs about 0.62 cubic yards of topsoil; the same footprint filled 12 inches deep for a raised bed needs about 3.70 cubic yards — six times more, because raised-bed soil goes six times deeper than a lawn topdressing layer. “How much topsoil do I need” only has one answer once you know which of those two jobs you’re doing — the depth, not the area, is what makes the totals so different.

Topdressing a lawn: 2 to 4 inches

Topdressing spreads a thin layer of topsoil over an existing lawn to level low spots, smooth out ruts, and improve the soil a new layer of seed roots into. 2 inches is enough for a light leveling pass on a lawn that’s basically flat; 4 inches is closer to a regrade, and is also the depth to aim for when prepping bare or heavily patched ground before sod or a full reseed. A 20 × 30 ft lawn topdressed at 2 inches needs about 3.70 cubic yards of topsoil — 4.07 cubic yards once you add the standard 10% waste allowance — which works out to 147 bags of 40 lb topsoil. Run your own lawn’s footprint through the topsoil calculator rather than scaling that number by eye; area and depth both move the total, and the calculator does the multiplication for you.

Topdressing pairs naturally with seeding — a fresh soil layer gives new grass seed something loose to root into instead of compacted, thatch-covered ground. Once the topsoil is down, size the seed order for the same footprint with the grass seed calculator.

Filling a raised bed: 10 to 12 inches

A raised bed needs far more depth than a lawn because vegetables and most garden plants build root systems a lawn never does — 10 to 12 inches gives roots enough loose, unrestricted soil to develop properly, versus the few inches a lawn’s root zone actually uses. An 8 × 4 ft bed (a standard raised-bed size) filled 12 inches deep needs about 1.19 cubic yards of topsoil, or 1.30 cubic yards with the standard 10% waste allowance — 47 bags of 40 lb topsoil. Change the depth field on the topsoil calculator to 10 or 12 inches and it recalculates for your bed’s actual dimensions.

One distinction worth knowing before you order: topsoil is natural excavated soil, useful as fill and for leveling or regrading, but it isn’t heavily amended. Garden soil is topsoil blended with compost and other amendments so it’s ready to plant into directly. Many raised-bed builds mix straight topsoil with compost or bagged garden soil rather than filling entirely with topsoil, since raw topsoil alone tends to compact more and carries less organic matter than plants growing in a contained bed need.

The formula: area times depth, divided by 324

Both jobs run on the same math — only the depth changes. Multiply length by width in feet to get the area, multiply by depth in inches, and divide by 324 (12 inches per foot times 27 cubic feet per yard):

cubic yards = (area × depth) ÷ 324

A 10 × 10 ft bed at the calculator’s default 4-inch depth is 10 × 10 × 4 ÷ 324 ≈ 1.23 cubic yards — 1.36 cubic yards after the standard 10% waste, or 49 bags of 40 lb topsoil. Swap in 2, 3, or 12 inches for the same footprint and the only thing that changes is the numerator.

Bags vs. bulk: what topsoil actually costs

A 40 lb bag of topsoil holds about 0.75 cubic feet (0.0278 cubic yards), so it takes about 36 bags (27 ÷ 0.75) to equal one cubic yard. As of 2026-07, bagged topsoil typically runs $2–5 per 40 lb bag, which puts a full cubic yard bought in bags at roughly $70–180 — call it $125 for a mid-grade bag. Bulk topsoil delivered by the yard is cheaper per unit, typically $15–40 per cubic yard for standard fill-grade soil, but suppliers add a delivery fee — commonly $50–150 — and often set a minimum order.

For most single raised beds, the total is well under a cubic yard, so bagged topsoil is the practical choice: no delivery minimum, no leftover pile to store. Past roughly 2 to 3 cubic yards — a full lawn topdressing or several beds at once — bulk delivery is typically cheaper even after the delivery fee, and the gap widens the more you order. Price both routes for your specific total from the calculator before deciding; the breakeven point moves with local delivery fees and soil grade.

What changes the total

• Bulk density. A cubic yard of topsoil weighs about 2,000–2,700 lb depending on moisture and how much sand, clay, or organic matter it contains — wetter soil weighs noticeably more, which matters for delivery trucks as much as for garden carts.
• Vehicle payload. A pickup truck bed typically maxes out around 1–1.5 cubic yards of topsoil before exceeding its payload rating, so confirm capacity before hauling bulk soil yourself rather than having it delivered.
• Waste allowance. 10% is the standard buffer for settling and uneven grading; drop to 5% only if you’re confident in the measurements and the ground is already close to level.

If the project includes ornamental beds rather than a raised vegetable bed, topsoil is usually just the grading layer — mulch goes on top once the soil underneath is level. Run that same footprint through the mulch calculator once your topsoil is graded.

Updated: 2026-07-15