Topsoil calculator
Soil is the one bulk material that arrives smaller than ordered. It settles, it compacts, and a cubic yard spread 6 inches deep covers less than the arithmetic says because the arithmetic assumes fluff.
Area to fill
How this is calculated
- Area = length × width.
- Finished volume = area × (depth ÷ 12), in cubic feet.
- Order volume = finished × (1 + compaction), because loose screened soil contains air that disappears after watering.
- Weight at roughly 1.2 short tons per cubic yard for moist loam — a number that varies from 1.1 to 1.4 depending on clay and water content.
Worked example
A 30 × 20 ft area at 6 inches, 15% compaction:
- Area = 600 sq ft; finished volume = 600 × 0.5 = 300 cu ft = 11.1 cu yd
- Order volume = 300 × 1.15 = 345 cu ft = 12.8 cu yd
- Weight ≈ 12.8 × 1.2 = 15.4 tons
Ordering 11 yards instead of 13 leaves a 2-inch shortfall across a 600 sq ft area — visible as soon as it is watered in, and impossible to fix without a second delivery charge.
Screened, unscreened and "fill dirt"
These are three different products and only one is topsoil:
- Screened topsoil — passed through a screen, organic matter present, suitable for planting. Expect $25–45 per cubic yard delivered.
- Unscreened loam — cheaper, contains rocks and roots. Fine under a lawn, not for a bed you will plant into.
- Fill dirt — subsoil, little organic content, compacts hard. For raising grade, not for growing anything.
If a supplier cannot tell you the organic matter percentage or the source, it is fill dirt with a better name. Ask for the test or buy from someone who has one.
Where the soil itself decides
- It does not fix drainage. Adding 6 inches of topsoil over a compacted subsoil creates a bathtub; the water has nowhere to go.
- It does not test your soil. pH, phosphorus and texture determine whether you need compost rather than more dirt.
- It does not account for existing grade. Filling a slope to level takes far more volume than area × depth.
- It does not cover amendments. Compost, sand and lime are separate volumes at different rates.
Questions people actually ask
How many cubic yards of topsoil do I need?
Area in square feet × depth in inches ÷ 324 gives cubic yards. A 600 square foot area at 6 inches needs 11.1 cubic yards finished, so order about 13 to allow for settlement.
How much does a cubic yard of topsoil weigh?
Roughly 1.1 to 1.4 short tons, depending on clay content and moisture. Moist loam is about 1.2 tons per cubic yard, which is 2,400 pounds.
How deep should topsoil be for a new lawn?
Four to six inches of good topsoil, incorporated into the existing soil rather than dumped on top. Less than four inches dries out too fast.
Is topsoil the same as fill dirt?
No. Topsoil contains organic matter and supports plant growth; fill dirt is subsoil with little organic content that compacts hard. They are not interchangeable and fill dirt is much cheaper.