Builder's Math

Construction calculators for your next project

Buy the right amount the first time. Get a shopping list of bags, sheets, bundles and posts for concrete, fences, roofs, drywall and more, with the math and sources shown. Free, no sign-up, and it works on your phone at the store.

Start from a common job

Concrete and landscaping

Masonry, walls and fencing

Floors and walls

Decks, framing and roofing

For suppliers and contractors

Put these calculators on your own website, with your logo and your products, and receive quote requests that already include the customer’s quantities: bags, yards, posts or sheets. We’re talking to a small number of lumber yards, concrete and landscape suppliers and installers before building it.

Ask about a calculator for your business How it works

Why use these calculators

  • Answers in what the store sells: bags, bundles, sheets, tons and gallons, not just volume.
  • Feet and inches the way you measured: type 12 ft 6 in straight in, or use yards, meters or centimeters.
  • Quick-answer tables for common sizes, and the math with a worked example on every page.
  • Save, share or print an estimate to take to the store or send to a contractor.
  • Works on the job site: add it to your phone’s home screen and pages you have opened keep working without signal.
  • Nothing to install or sign up for. The numbers you type stay in your browser.