About BuildCalcs

BuildCalcs is a free tool site for builders, contractors, and serious DIYers. It turns the dimensions you already know — a slab's footprint, a roof's pitch, a room's walls — into the numbers you actually order with: cubic yards and bag counts, sticks of rebar, squares and bundles of shingles, tons of hot mix, sheets of drywall.

Where the numbers come from

The formulas are the standard ones — geometry for volumes, the pitch multiplier √(1+(rise/12)²), unit weights for rebar, published yields for bagged concrete. The rule-of-thumb consumables (screws per square foot, mud per 500 sf, pickets per hundred feet) and the cost bands are compiled in September 2026 from published construction cost guides and manufacturer coverage figures. Where a number is a ballpark, every page says so — cost figures are budgeting bands, not quotes, and regional reality swings hard.

What this site is not

It is not engineering, and it is not a quote. Structural decisions, code compliance, and anything with a stamped drawing belong to your engineer and your local building department — the IRC and manufacturer numbers here are the model-code baseline as of September 2026, and local amendments change them. Every calculator documents its assumptions so you can argue with the output; that's the point.

Privacy in one line

All calculations run in your browser. Nothing you type into a calculator is stored, uploaded, or sent anywhere. See the privacy policy for the full story.

Questions or corrections? Contact us — formula corrections and rule-of-thumb improvements are genuinely welcome.