How much soil for raised beds, lawns, and grading? Cubic yards, tons, and bag counts. Free with steps.
Raised beds, new lawns, and regrading all hunger for topsoil — and soil is sold by the cubic yard, a unit nobody can picture. One cubic yard is 27 cubic feet: about a washing-machine-sized heap that weighs over a ton. Our free Topsoil Calculator turns your bed dimensions and target depth into cubic yards, tons, and the equivalent bag count, automatically adding 25% extra for the settling that turns a full-looking bed into a hollow one within weeks.
The settling factor is the heart of soil math. Loose delivered soil consolidates roughly 20% as water and gravity collapse its air pockets — a bed filled level to 12 inches of loose soil finishes near 9.5 inches. Ordering for the finished depth guarantees a second order; the calculator orders for the loose depth so you finish where you aimed.
Screened loam, garden mix, and compost blends all estimate the same way; only the density (and price) changes. Use feet, yards, or meters for the footprint and inches for depth, the way garden plans are drawn.
Topsoil is the upper, darkest, most biologically active layer of soil — typically the top 2–8 inches — rich in organic matter and microorganisms. What quarries sell as “screened topsoil” is this layer harvested, screened to remove rocks and roots, and piled for sale. Quality varies enormously: good loam is roughly 40% sand, 40% silt, 20% clay; cheap “fill dirt” may be nearly pure clay that drowns roots.
Plants experience soil as texture, structure, and biology. Texture (the sand-silt-clay ratio) sets drainage; structure (crumb vs. compacted) sets root penetration; biology (fungi, bacteria, worms) unlocks nutrients. Raised-bed mixes cheat by blending: one-third topsoil, one-third compost, one-third aeration (perlite or coarse sand) — the famous “Mel’s Mix” ratio that forgives mediocre components.
Depth targets follow roots: lawn grass thrives in 4–6 inches of good soil over loosened subsoil; most vegetables want 8–12 inches; carrots and parsnips demand a full 12+ inches of stone-free depth. Deeper is not always better — beyond 18 inches, unimproved native subsoil usually outperforms imported soil on cost — but too shallow starves everything.
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Soil density swings with moisture: dry screened loam ~0.9 tons/yd³, saturated ~1.3. Suppliers sell by the yard (volume), so wet or dry, the yardage — and the calculator’s answer — stays the same.
One raised bed: 8 ft long, 4 ft wide, 12 inches finished depth.
Order 1.5 cubic yards bulk (~$75) instead of 20 bags (~$140) — and save your back. Four such beds need 6 yards: one small dump-truck load.
A 2,000 ft² lawn needs 1 inch of compost topdressing to revive tired turf.
Order 8 cubic yards. That is a full tri-axle load — coordinate delivery with a dry day, because 8 yards of compost will not wait politely in the driveway.
Twelve volunteers are building six raised beds, each 8 × 4 ft at 12 inches finished depth, for a community garden. Per bed: 1.48 yd³ (from the worked example); six beds: 8.9 yd³ — call it 9 yards of 50/50 garden mix at $55/yard = $495 delivered. The bagged alternative (120 bags at $7) would cost $840 and require a full extra volunteer day of hauling. The cubic-yard estimate, done in two minutes, saves $345 and a Saturday.
The build-day lesson is staging. Nine yards arrives as a single heap roughly 10 ft across and 4 ft tall. Wheelbarrows move ~3 ft³ per trip: 9 × 27 ÷ 3 = 81 trips. With four wheelbarrows running, that is about two hours — the schedule the organizers built only because the volume math told them the trip count in advance.
A second scenario: fixing a low spot. A 15 × 10 ft section of lawn sits 3 inches below grade and ponds after rain. Fill needed: 150 ft² × (3 × 1.25/12) ft ÷ 27 = 1.74 yd³ — order 2 yards of topsoil, spread, compact lightly, and re-sod. Without the settling factor, the spot would pond again by fall.
The soil triangle classifies every soil by its sand-silt-clay percentages, and the triangle’s sweet spot — loam — is what “good topsoil” means. Clay particles are microscopic plates that stack into waterproof layers; sand grains are boulders by comparison that drain instantly. Silt splits the difference. The estimator’s field test: squeeze a moist handful — loam holds shape briefly then crumbles; clay ribbons between your fingers; sand falls apart immediately.
Bulk density ties volume to weight: undisturbed loam runs ~1.3 g/cm³ (~1.1 tons/yd³), compacted clay hits 1.6+. Roots struggle above ~1.5 g/cm³ because pores collapse. This is why rototilling wet clay is vandalism — it destroys structure and spikes bulk density — while amending with compost lowers density and opens pores. Volume math gets the soil there; physics decides whether roots thrive.
Compost math has its own ratio: the carbon-to-nitrogen ratio. Finished compost (~25:1) feeds soil biology; fresh wood chips (~400:1) rob nitrogen as microbes digest them. Topdressing beds with uncomposted chips yellows plants — not from the chips’ chemistry but from nitrogen theft. Mix chips into paths, compost into beds.
Finally, the soil food web: a teaspoon of healthy soil holds more microbes than people on Earth. Those microbes mineralize organic matter into plant-available nutrients, which is why biologically alive topsoil outperforms sterile bagged “soil” that is mostly peat and perlite. Inoculating beds with a shovelful of forest soil or quality compost jump-starts the web — volume you can estimate, biology you must cultivate.
Topsoil estimate: loose depth = finished inches × 1.25 (settling); cubic yards = L×W×(loose ft)/27; tons ≈ yd³×1.1 (moist loam). Depths: lawn 4–6 in, vegetables 8–12 in. Bulk beats bags past ~10 bags. Verify loam texture; loosen subsoil; keep soil below siding. Source: Sigma Calculator, Topsoil Calculator, https://sigmacalculator.net/math-calculators/topsoil-calculator/
Cite this page as: Topsoil Calculator, Sigma Calculator, https://sigmacalculator.net/math-calculators/topsoil-calculator/
Last updated: October 12, 2026