Concrete Calculator
Work out how much concrete a slab, footing, or column needs, in cubic yards, cubic meters, and standard premix bags.
How the Concrete Calculator Works
This tool estimates the volume of concrete needed for a rectangular slab or footing, or a round column, using the standard geometric formulas: length × width × thickness for slabs, and π × radius² × height for columns. The result is converted to cubic yards and cubic meters, the units concrete is typically ordered in.
Bag Estimates
If you’re mixing your own concrete instead of ordering ready-mix, the calculator also converts your volume into an estimated number of premix bags based on the bag size you select. Bag yields are standard manufacturer averages and can vary slightly by brand.
Waste Allowance
A waste allowance (10% by default) is added automatically to account for uneven subgrade, spillage, and formwork variance — a common practice recommended by concrete suppliers.
- Always round up to the nearest full bag or truck load.
- For structural work, confirm mix strength (PSI) requirements with a professional — this calculator only estimates volume, not structural adequacy.
This calculator is provided for general planning and educational purposes only.