What this calculator does
The topsoil calculator estimates soil needed to cover or fill a rectangular area to a chosen depth. It focuses on cubic feet and cubic yards, with optional bag equivalents and optional weight when density is entered.
Formula overview
Dimensions are normalized to feet before calculating length times width times depth. Cubic feet are divided by 27 to estimate cubic yards. Waste allowance is applied to volume.
Volume and weight
Topsoil is usually planned by volume, but suppliers may price by cubic yard or by ton. Weight estimates require an entered density and should be treated as moisture-dependent planning numbers.
Worked example
A 12 ft by 8 ft area at 6 inches deep is 96 square feet. A 6 inch depth is 0.5 ft, so the raw volume is 48 cubic feet, or about 1.78 cubic yards. With a 10% allowance, the estimate is about 1.96 cubic yards.
Assumptions and limitations
This tool estimates rectangular areas. It does not evaluate soil quality, drainage, grading, compaction needs, or planting requirements.