Tools

Free Home Project Calculators

Small calculators for the decisions that cost real money. Each one uses published prices, names the source, and shows the date of the figures on the page. Nothing is sent anywhere. The arithmetic runs in your browser.

We'd rather leave a line blank than invent a price for it. Where no source gives a number, the tool asks for the one on your own quote.

How these calculators are built

Every tool on this page follows the same four rules. The arithmetic is a plain function you could check with a pencil, so there is no model guessing at a price and no server that sees your inputs. Each constant comes from a named source, and the date of that source is printed next to the result, because a 2026 price quoted without a date is a trap by next spring.

The third rule is that a gap stays a gap. If no published source gives a dollar range for a cost, the tool asks you for the figure from your own quote and counts it as zero until you type one. We would rather show a total that is honestly incomplete than one that looks finished and is padded with a number we made up.

The fourth rule is that a result may tell you something inconvenient. Doing a job yourself is not always the cheaper route once you count the bags, and a calculator that only ever says yes to the purchase is a sales page with arithmetic on it. Expect the odd result that says hire someone.

Looking for the reasoning behind the numbers? The how-to guides explain each project, and the cellulose cost breakdown is the source for the first calculator.