Construction calculators

How to use these construction calculators

Every calculator works the same way: enter the measurements you took on site, and the quantity updates as you type. Nothing is sent anywhere — the arithmetic runs in your browser, so the tools work on a phone with a poor signal.

Each page prints the formula it uses, along with a worked example you can check by hand. If a result disagrees with your own figure, you can see exactly where the two calculations diverge rather than having to trust a black box.

Material estimating in three steps

1. Measure the area or run, splitting anything irregular into rectangles and triangles you can add together.
2. Decide the depth or thickness. This is where most ordering errors happen — depth affects quantity in direct proportion, and a one-inch mistake on a driveway is several tons.
3. Add a waste allowance. Five to ten percent on bulk materials, 10 to 20 percent on anything cut to fit. Where a calculator applies one, it says so and shows the exact requirement alongside.

Why the formula is always shown

A material estimate that you cannot check is a number you have to take on faith, and faith is expensive when a delivery arrives short. Every formula here comes from published trade practice or a code table, stated on the page, with the source given in our methodology.

Between them these calculators cover about 523,530 searches a month. If the one you need is missing, tell us — suggestions from real jobs are how the list grows.