About ConcreteCalc

ConcreteCalc turns pour dimensions — slabs, footings, round columns and steps — into cubic yards, premix bag counts and rough costs. It runs entirely in your browser and costs nothing.

How it calculates

Every shape is reduced to cubic feet with schoolbook geometry: length × width × thickness for slabs and footings, π × radius² × height for columns, and a stacked-box sum for steps. Cubic feet convert to cubic yards by dividing by 27, and to cubic metres using the exact foot definition (1 ft = 0.3048 m). Bag counts divide the waste-adjusted volume by the yield printed on standard premix bags — 0.60 ft³ for an 80 lb bag, 0.45 for 60 lb, 0.375 for 50 lb and 0.30 for 40 lb — and always round up. Those yields are the figures major US manufacturers publish for their premix bags; individual brands vary slightly, and the label on your bag is the final word.

What it is not

ConcreteCalc is a planning tool. It does not design slabs, set thicknesses, size footings or check loads, and nothing here replaces your local building code, a permit drawing or an engineer where one is required. Prices in the cost tools are figures you enter for comparison — concrete pricing is local, and only quotes from plants and stores near you mean anything.

Who runs it

ConcreteCalc is part of a small family of free calculators built and maintained by ORBITFRAME. Questions or corrections: the fastest route is the contact option on the main ORBITFRAME portfolio site.