Concrete calculator
Measure the slab or column, add a little extra for waste, and see how much concrete or how many bags you need.
Questions people ask
How do I calculate concrete for a slab?
Multiply length × width × thickness in the same unit. A 10 ft × 10 ft slab 4 inches thick is 10 × 10 × 0.333 = 33.3 ft³, or 1.23 cubic yards (27 ft³ each).
How much extra should I order?
5–10% is common to cover uneven ground, spillage and form bulges. For ready-mix deliveries, round up to the supplier’s ordering step, often a quarter or half yard.