Topsoil Calculator

The depth of topsoil required depends entirely on what you are growing and what is already in the ground. A new lawn from seed or sod needs 3–4 inches of quality topsoil to give grass roots a nutrient-rich medium to establish in. Vegetable gardens require 6–8 inches minimum so that root crops like carrots and beets can develop fully. Raised beds work best at 10–12 inches deep. Topdressing an existing lawn — a thin layer worked into the turf to improve soil structure over time — typically uses only 1/4 to 1/2 inch. To convert your target depth into an order quantity, multiply the area in square feet by the depth in feet (depth in inches divided by 12), then divide by 27 to get cubic yards. One cubic yard covers 108 sq ft at 3 inches or 81 sq ft at 4 inches. Always add at least 10% to your calculated volume to account for compaction: fresh topsoil settles 10–15% as water collapses air pockets in the first weeks after placement, and you do not want to come up short after the delivery truck is gone.

Bulk topsoil delivered by truck is dramatically cheaper than bagged topsoil for any project requiring more than one cubic yard. Bulk screened topsoil typically costs $30–60 per cubic yard plus a $50–100 delivery fee, depending on your region and supplier. Bagged topsoil runs $5–9 per cubic foot bag at a home center — that works out to $135–243 per cubic yard, three to five times the bulk price. The break-even point is roughly 1–1.5 cubic yards: below that, hauling bags from a store makes sense; above it, a bulk delivery almost always wins. Quality also tends to be better with bulk suppliers, because you can inspect the product before delivery and specify screened versus unscreened, loam-based versus sand-amended, or topsoil-compost blend. Ask your supplier for a recent soil test report — reputable bulk suppliers will have one. The test should show pH in the 6.0–7.0 range, organic matter above 3%, and no detectable heavy metals or herbicide residue if the source is recycled material.

Not all topsoil is equal. The best screened topsoil is loam-based — a balanced mixture of sand, silt, and clay — with 3–5% organic matter, a pH of 6.0–7.0, and a dark brown color from humus content. It should feel moist but not sticky, crumble when squeezed rather than forming a hard clod, and have a mild earthy smell — not a sulfurous or chemical odor. Avoid topsoil that is visibly sandy (drains too fast, holds no nutrients), heavy clay (compacts and waterlogging), or contains excessive debris like roots and rocks. Be especially cautious with recycled topsoil from construction sites: it may be subsoil (lighter in color, lacking organic matter), contaminated with fill material, or contain herbicide residue from previous agricultural use. If you are filling a large area and quality topsoil is expensive, use lower-cost fill dirt for the bottom 6–8 inches and premium screened topsoil for the top layer where roots will actively grow.

Applying topsoil over compacted or hard-pan native soil without preparation creates a layering problem: roots develop in the soft new topsoil but hit a hard transition layer and stop, creating a perched water table and stunted plants. Before placing new topsoil, till or loosen the existing soil to a depth of 4–6 inches using a rototiller or garden fork. This breaks up compaction, allows drainage to continue through the soil profile, and creates a rough surface that the new topsoil can bond to mechanically. On slopes, roughing up the existing surface also prevents the new topsoil layer from sliding. For large lawn renovations, a soil core aerator followed by vertical slicing gives the best mechanical integration between new and old soil. If the native soil is extremely poor — dense clay subsoil from construction, for example — consider a thicker topsoil layer (6+ inches) and accept that roots will be largely confined to that layer for the first several years until organic activity builds soil structure below.

Fresh topsoil is loosely compacted during production and delivery — it contains significant air pore space that collapses under watering and foot traffic. Expect 10–15% settlement in the first month after placement. For a project requiring a finished grade exactly level with an adjacent surface (such as a patio or driveway), place and lightly compact the topsoil 10–15% higher than your target grade to account for this settling. A plate compactor set to a light pass, or simply walking over the area while watering, is sufficient — you do not want to fully compact topsoil or you will eliminate the pore space that makes it valuable for plant growth. If you are grading for positive drainage away from a foundation, maintain a minimum 6-inch drop in the first 10 horizontal feet per IRC guidance. Finish grading before seeding or planting, since regrading after plants are established causes damage and defeats the purpose of the preparation work.