About

DIYCalcs is a collection of 41 free calculators for home improvement and landscaping projects. Each one answers a single practical question — how many bags of concrete, how many cubic yards of mulch, how many gallons of paint — so you can buy the right amount the first time.

Who builds it

DIYCalcs is built and maintained by a software engineer with a strong background in automation, who is interested in the DIY world as a hobby. That background shapes how the site works: every formula is written as code, checked by automated tests against examples worked out by hand, and the same code produces the results, the drawings and the worked example on each page.

The site’s author is not a contractor or a structural engineer, so the numbers come from standard geometry and published sources (manufacturer data sheets, university extension guides and building codes) rather than personal rules of thumb. Wherever safety or structure is involved, the pages point you to local codes and a licensed professional.

How the calculators work

Every calculator uses published, standard formulas: geometric volume and area, manufacturer coverage rates (for example, the yield printed on a bag of concrete mix or the spread rate on a can of paint), and typical material densities. Each page explains its formula, shows a worked example, lists the assumptions it makes and ends with a Sources list linking the data sheets, extension guides and code sections behind its numbers, so you can check the math yourself.

The formulas are covered by automated tests that run every time the site changes, and the example on each page is generated by the same code that runs the calculator, so the two can never disagree.

Accuracy

Quantities are estimates. Real projects vary: ground is uneven, boards warp, products differ between brands. We suggest a waste allowance where it matters, and you should always confirm critical quantities with your supplier and follow local building codes. See our terms and disclaimer.

How this site is funded

The calculators are free to use. The site shows advertising and some pages link to products through affiliate programs, which pay us a small commission at no extra cost to you. Advertisers never influence the formulas or results.

Contact

Found a mistake or want a calculator we don’t have? Tell us through the contact form.