Calculate concrete volume for slabs, footings, columns, and stairs. Estimate bags needed and total cost. Supports metric and imperial units.
Our free Concrete Calcolatore helps you estimate the volume of concrete needed for slabs, footings, columns, and stairs. Simply enter your dimensions, select your unit system, and get instant results including the number of concrete bags required and total cost estimate. All calculations run locally in your browser — no data is sent anywhere.
For a concrete slab, multiply the length × width × depth (thickness). For example, a 10 ft × 10 ft slab that is 4 inches thick needs about 1.23 cubic yards of concrete. Our calculator does this automatically and adds a waste factor.
A typical waste factor is 5-10%. Use 5% for simple, flat pours. Use 10% or more for complex shapes, stairs, or if you are inexperienced with concrete work.
It depends on the bag size and total volume. A standard 80 lb (36 kg) bag yields about 0.6 cubic feet (0.017 m³). Enter your bag size in our calculator and it will tell you exactly how many bags you need.