Slab and footing formulas

Multiply length × width × thickness × quantity in meters. A 6 × 4 m slab, 120 mm thick, has a net volume of 2.88 m³. Adding 5% waste gives 3.024 m³.

V slab = L × W × T × N

V pad = L × W × H × N

V tapered = [A×B×h₀ + h₁/6 × (A×B + a×b + (A+a)(B+b))] × N

Defaults are 5% for slabs, 7% for footings, 3% for columns and 5% for beams. Adjust for formwork, ground conditions and delivery methods.

Rates per 1 m³; multiply by gross volume including waste. Cement bag size: 50 kg.