Work out how much material you need — before you buy it

Why this site exists

Most “free calculator” pages exist to collect an email address or to load a stack of tracking scripts before showing you a number. Materials estimating is the worst offender: you get a single input box, no formula, and no indication of what happens when your slab has a thickened edge.

Every page here is one tool, written in plain HTML, CSS, and JavaScript, with the arithmetic shown next to the result. Your measurements stay in your browser's memory and disappear when you close the tab.

• No account, no upload. Slab dimensions and income figures never reach a server.
• Answers in the first screen. The calculator is at the top of the page. The explanation sits below it, where you can ignore it if you already know what you need.
• Real formulas, real sources. Bag yields come from manufacturer packaging, rebar limits from ACI 318, and tax figures from IRS publications — each page names its source and states what it does not model.
• Works on a phone at the job site. Pages are lightweight and keep working once loaded, even with a weak signal.

How to get a number you can order from

Start with the volume calculator for your material, then add waste. Concrete needs 5% to 10% extra because running short mid-pour creates a cold joint, and returning unused ready-mix costs money anyway. Lumber is better ordered with 10% to 15% waste on framing, because defects and miscuts are normal.

Every page shows a worked example with real numbers so you can sanity-check your own result. If your figure is far off the example, check the units first — mixing inches and feet is the single most common estimating error.

Frequently asked questions