About Concrete Calculator

What we do

We build calculators that tell you how much concrete a project needs, and guides that explain the math, the materials and the ordering process. The tools cover slabs, footings, columns, walls, stairs, curbs, driveways, bags, weight, cost, blocks, rebar, gravel and mix ratios.

The goal is simple: give a homeowner or builder an answer they can write on a shopping list or read to a ready-mix dispatcher, and show how the number was reached so they can check it.

How the numbers are made

Every calculator uses one shared formula engine. The numbers you read in the guides, charts and size pages are produced by the same engine at build time, so a figure on a page and the same inputs in the calculator cannot disagree. The engine is covered by automated tests that compare results with hand-checked values before each release. The methodology page lists the formulas, constants and sources.

Who this is for

Homeowners planning a patio or walkway, DIY builders pouring a shed pad, post holes or steps, and small contractors who want a quick check of a quote. Large structural pours need an engineer and a mix design, and our tools say so where it matters.

How the site is paid for

The site is free to use. We may show advertising from Google AdSense to cover hosting and development. Ads are labeled and kept away from calculator inputs and results. We do not sell your calculations. See the privacy policy for details.

Independence

Brand names such as Quikrete and Sakrete are used only to cite published product data. This site is not affiliated with any brand. We do not accept payment to change a calculator result or a recommendation.

Corrections and feedback

If you find a mistake or have a suggestion, write to hello@concretecalculator.org. We check reports and fix confirmed errors, and note the date a page was last updated at the top of it. Our social profiles are on X and Facebook.

There is also a free browser extension: Concrete Calculator for Chrome.