Volume formula
For a rectangular slab, multiply length by width to get area, then multiply area by thickness. The calculator normalizes each dimension before calculating and reports the result in cubic feet, cubic yards, and cubic meters.
For example, 10 ft × 10 ft × 4 in is 33.33 cu ft, or about 1.23 cu yd, before waste. This is a hypothetical arithmetic example, not a recommended slab specification.
Ordering concrete
Use raw volume as a geometric estimate, then consider whether a waste allowance is appropriate. Supplier minimums, truck capacity, access, pumping, and delivery terms may change what you should order. Verify quantities and ordering rules directly with the supplier.