About

DIYCalcs is a collection of 26 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.

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 and lists the assumptions it makes, 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 may show advertising. Advertisers never influence the formulas or results.

Contact

Found a mistake or want a calculator we don’t have? Email hello@diycalcs.org.