About CalcPit

87 construction and landscaping calculators that show their working.

Why this exists

Most material calculators online do one of two things wrong. Either they hide the formula, so you have no way to know whether the number is right, or they bury the tool under a thousand words of filler before you can type anything.

CalcPit does the opposite. The calculator is the first thing on the page. The formula it uses is printed underneath it, along with a worked example you can check by hand. If our number disagrees with yours, you can see exactly where.

How the numbers are checked

Every calculator carries test cases that were worked out by hand from the reference formula — never by running the calculator and recording what it said, which would only confirm a bug rather than catch it. The site does not build if a single one of those cases fails.

A second check runs against the finished pages: it extracts the JavaScript that actually ships to your browser and verifies that it computes the same answers. A formula that is correct in our source but broken on the page would pass the first check and fail the second.

Where a figure depends on a standard — concrete cover, conductor ampacity, roof pitch conventions — we say which standard, and we say when a value is a trade rule of thumb rather than a code requirement. See our methodology for the sources behind each category.

What we don't do

No account. No email capture. No cookie banner, because there are no cookies to consent to. The measurements you type never leave your browser — the arithmetic happens on your device, not on our server.

Who publishes it

CalcPit is published by an independent publisher. Corrections and questions are genuinely welcome — if you find a formula you disagree with, tell us and cite your source. We will either fix it or explain why we think it is right.