Method

Results are estimates. Confirm quantities with your supplier before ordering.

• Volume materials (concrete, gravel, mulch, topsoil): area × depth ÷ 12 gives cubic feet; ÷ 27 gives cubic yards. Circles use π × (diameter ÷ 2)². Waste is added as a percentage.
• Shapes: circle π × d² ÷ 4; ring π × (D² − d²) ÷ 4; right triangle base × height ÷ 2; L-shape length × width − notch; trapezoid (top + bottom) ÷ 2 × height; footing length × width × depth; column π × r² × height; post hole (π × r² − post area) × depth; steps width × rise × run × n(n+1) ÷ 2.
• Custom outline: area by the shoelace formula from the corner positions; perimeter is the sum of the sides.
• Bags: cubic feet ÷ bag yield (80 lb concrete 0.6 cu ft, 60 lb 0.45, 40 lb 0.3), rounded up.
• Weight: cubic yards × typical density (concrete about 2.0 tons, gravel 1.4, topsoil 1.2 per cubic yard).
• Paint: (2 × (L + W) × height − 20 sq ft per door − 15 sq ft per window) × coats ÷ coverage per gallon.
• Tile: area × (1 + waste) ÷ tile area. Grout lb = (tile width + length) ÷ (width × length) × joint × thickness × area × 1.86. Thinset about 80 sq ft per 50 lb bag.
• Flooring: area × (1 + waste) ÷ sq ft per box, rounded up.
• Drywall: surface × (1 + waste) ÷ sheet area; about 1 screw per sq ft, 9.4 gal compound and 370 ft tape per 1,000 sq ft.