About SquareFootCalcs

SquareFootCalcs is a set of 10 free material calculators for home and yard projects. You enter the measurements; it tells you how much to buy. No account, no app, no email address.

Why it exists

Every material calculator online gives you a number. Very few tell you where the number came from, and almost none handle a shape that is not a perfect rectangle — which is most real patios, beds and rooms. These pages show the formula and a worked example underneath the tool, let you split an irregular area into as many rectangles as you need, and accept feet-and-inches written the way people actually write it.

Where the reference figures come from

Bag yields, coverage rates and depth recommendations are the values published by the major manufacturers and the standard trade rules of thumb. Each calculator page lists the figures it uses in a table, and the date they were last checked appears under the tool.

These numbers vary between brands and product lines. Where a page says to check the label, that is not boilerplate — a 0.05 cubic foot difference in bag yield is a missing half-yard of concrete across a large pour. The calculators are for deciding what to buy; the label on the product is the authority for the product you actually bought.

What these calculators are not

They are estimating tools, not engineering calculations. They will tell you how many bags of concrete a slab takes. They will not tell you whether the slab is thick enough for what you are putting on it, whether it needs reinforcement, or whether your local code requires a permit. For anything structural, ask someone who can see your site.

How it is built

A static site built with Astro. Every page is pre-rendered HTML; each calculator is a small isolated component that only loads when you open its page. Nothing you type is sent anywhere — the arithmetic happens in your browser, which is also why the calculators keep working with a bad connection.

The shared conversion and rounding code is covered by unit tests, because a unit-conversion bug is the one failure mode that would quietly waste people's money.

Corrections

If a figure looks wrong, or a calculator does not handle a case you have in front of you, thecontact page is the place to say so.