About us
CementCalc builds free concrete, masonry and aggregate calculators for contractors, estimators and homeowners.
Quick answer
What we do
Ordering concrete is unforgiving: a short load means a cold joint, and an over-order means paying for concrete that goes in the spoil pile. CementCalc exists to make that one decision — how much material to buy — fast and repeatable, whether you are pouring a 10 x 10 shed slab or setting 40 fence posts.
We cover slabs, footings, columns, steps, curbs, post holes, bag counts, ready-mix and bagged cost comparisons, rebar grids, gravel and sand takeoffs, pavers and retaining wall block, plus reference charts for mix ratios, rebar sizes and curing times.
How the numbers are built
Volumes come from straight geometry in cubic feet, then convert at 27 cubic feet per cubic yard. Bag counts use manufacturer-published yields (an 80 lb bag of concrete mix yields about 0.60 cubic feet). Aggregate weights use standard compacted densities, and rebar weights are derived from bar designation in eighths of an inch.
Waste allowances are shown separately from the raw volume so you always see the base number. Full assumptions, densities and formulas are documented on our methodology page.
Editorial independence
CementCalc carries display advertising and affiliate links, disclosed on every page that uses them. Advertisers and retailers have no input on the calculators, the formulas, or which products are listed. See our affiliate disclosure for details.
Contact
Corrections, questions and feedback are welcome — the contact page has our email address. If you spot a number that looks wrong, tell us the inputs you used and we will check the formula.