About BuilderMath

What the site does

BuilderMath works out how much material a building job needs. You type the sizes the way a tape measure reads them, in feet, inches and sixteenths, and each calculator draws the job to scale, gives the total and lists what to buy in the units a store sells, with the extra for waste on its own line. The steps of the math are printed under every answer.

Where the numbers come from

Areas and volumes are geometry, and the unit conversions follow the legal definitions of the foot, the yard and the gallon, so they are exact. Everything else, such as how far a bag of concrete goes or how much extra a supplier advises, is taken from a named document: a manufacturer’s data sheet, an industry association’s guide or a building code. Each calculator lists its documents under Sources, with the date they were last checked. How BuilderMath calculates explains the rules every calculator follows.

Who runs it

The site is made and run by BuilderMath, and its pages are written under that name. It sells nothing and carries no advertising.

Corrections and contact

If a number looks wrong, write with the page, the sizes you typed and what you expected. We check it against its source. A fix goes into the calculator’s data, so every page that uses that number changes with it.

Corrections and questions: contact@buildermath.org.