Concrete volume
Volume = length × width × thickness · Bags = volume ÷ yield per bag
Keep all dimensions in the same unit, then convert to cubic yards (1 yd³ = 27 ft³) or cubic metres. A 80 lb bag yields ~0.6 ft³. Always add 5–10% waste for spillage, uneven subgrade and over-excavation so you don't run short during the pour.
How to estimate concrete for a slab
Enter length, width and thickness in whatever units you like — meters, centimeters, feet or inches. The calculator converts everything, computes the volume, and shows cubic yards, the number of pre-mixed bags, and cost, while the slab preview reshapes to your dimensions.
Add a waste allowance (5–10% is typical) to avoid running short during the pour.
Estimates only — confirm quantities with your supplier before ordering.