What we do
BuildMath.online publishes free calculators and reference charts for the math that comes up on real US jobsites: concrete and aggregate quantities, rebar and form lumber, stair stringers, rafters, roof pitch, wall studs, drywall, board feet and tape-measure fractions. Today the site covers 182+ pre-calculated sizes and presets, each with a live calculator you can adjust.
Who it's for
- Homeowners and DIYers planning a patio, shed pad, garden bed or basement finish.
- General contractors and carpenters who need a fast takeoff or a sanity check before ordering.
- Apprentices (carpentry, IBEW, plumbing) practicing fractions, layout and estimating math.
How our calculators work
Every result comes from a published formula — area × depth for volume, the Pythagorean theorem for rafters and stringers, nominal dimensions for board feet — written once in code and shared by the interactive calculator and the pre-calculated tables. US Imperial units come first: feet, inches, fractions to 1/16", cubic yards, pounds and tons. Each page includes a "How the math works" breakdown so you can check the numbers by hand.
Material yields and code limits come from the 2024 International Residential Code (IRC), ACI and ASTM references and published manufacturer data. Our full sourcing and review process is described in theEditorial Guidelines.
Our design principles
- Jobsite first: large inputs and buttons that work on a phone with gloves on.
- Waste included: every material calculator has a 0–15% waste factor, because real orders need it.
- Printable: shopping lists and cheat sheets print cleanly for the truck or the shop wall.
- Fast: no sign-up, no app install, and no heavy scripts.
Important limits
Calculators produce estimates. They are not a substitute for local building codes, a permit review or a licensed engineer's design. Always confirm quantities with your supplier and check local requirements before you build.
How the site is funded
BuildMath is free to use and supported by display advertising. Advertisers have no influence over our formulas, results or recommendations.
Who builds BuildMath
Content and calculations are maintained by the BuildMath Estimating Team. The website was designed and developed by ArtWeb.
Get in touch
Spotted a number that looks wrong, or want a calculator we don't have yet? Emailcontact@buildmath.online or use the contact form.