About BuildCalc

What this site is

BuildCalc is a set of 30 small calculators for the questions that come up once you pick up a paintbrush: how much paint a room needs, how many tiles cover a floor, how much concrete fills a post hole, how many shingles a roof takes, how much mulch a bed wants, and how big a solar or air-conditioning system your home really needs. Each one does a single job, loads instantly, and needs no sign-up, email or app install.

How the numbers are produced

Every calculator on this site runs entirely inside your browser. When you type a room size or a bag count, that value is processed by JavaScript on your own device. It is never sent to a server, because no server does the calculating. You can disconnect from the internet after the page has loaded and the calculators keep working.

That means your dimensions, measurements and project details stay on your device. Nothing about what you are building is logged, stored or shared, because it is never transmitted in the first place.

Where the formulas come from

Each calculator uses a standard, industry-accepted method rather than an invented one — the paint-coverage figure printed on a can, the spread rate of thin-set, the yield of a bag of concrete mix, or the rise-and-run rule that keeps a staircase comfortable to climb. The page under each tool explains what that method is, which measurements it needs, and where it stops being reliable.

We also tell you the limits. A quantity estimate is not a quote: coverage varies by surface and product, wastage creeps up on cut tiles and angled walls, and building codes, permit rules and structural requirements differ from place to place. Treat every result as an informed starting point, then check it against your own plans and local requirements.

Not construction advice

BuildCalc provides general information for planning and estimation. It is not a substitute for a licensed contractor, a structural engineer, an electrician or a building inspector, and it does not account for your local code. Do not rely on these calculators alone for structural, electrical or load-bearing work. See our full disclaimer.

Why it is free

The site is supported by advertising. Advertising is loaded only after you agree to it through the cookie banner, and the tools work exactly the same if you decline. We keep ads out of the working area of each calculator so they never interrupt what you are doing.

Corrections and requests

Found an error, or want a calculator that does not exist yet? Write to hello@buildcalchub.com. Corrections and reader requests are the main reason this site changes.