Methodology

Every calculator on BuildCalcs uses a published, repeatable formula. We list the formula and a worked example directly on each page so you can verify the math.

Units & conversions

Lengths default to feet and inches. Areas use square feet, with conversions to square yards and square meters where relevant. Volumes are computed in cubic feet then converted to cubic yards (÷ 27).

Waste factors

Calculators that consume material include an adjustable waste percentage (default 10%) to account for cuts, spillage and uneven subgrade. We always round material quantities up to the next whole unit so you don't come up short.

Material densities

Default densities (e.g. 1.4 tons/yd³ for crushed stone, 145 lb/ft³ for asphalt) match the values quoted by major US aggregate suppliers. You can override the density when your supplier publishes a different number.