About BuildCalc

What the site publishes

The site has two kinds of pages. The eight calculators take measurements and return quantities or layout dimensions for roofing, concrete, stairs, rebar, drywall, masonry, and general material waste. The guides explain one estimating task each, with a reference table, a worked example, and a list of common mistakes.

Dimensions are in US customary units because the code references and product sizes the site uses are North American. The audience is contractors, estimators, framing carpenters, and owners planning their own work.

Who runs this site

BuildCalc is built and maintained by WayPoint, an independent software developer. WayPoint writes the calculation functions, the reference tables, and the guides, and answers the email address on this page. The same name appears on the privacy policy and the terms as the site operator.

Nothing on the site is sealed, stamped, or reviewed by a licensed engineer or architect, and BuildCalc does not provide engineering, design, or code consulting services. Questions and corrections go to [email protected].

How a calculation is built

Each calculator is a plain TypeScript function. It takes the measurements you enter and returns numbers. The function runs in your browser, so the values you enter are not sent to a server. The reference tables in the guides call the same functions, which keeps a guide and its calculator from disagreeing.

• Order quantities round up. Sheets, bags, bundles, and bars are whole units, so the engines round up after waste is applied.
• Waste is a separate, visible step. Each calculator shows the net quantity and the quantity with waste, so you can see what the allowance adds.
• Displayed values are rounded. Internal arithmetic keeps full precision. Display rounding can differ from a hand calculation by the last digit.

Where the numbers come from

• Stairs. Maximum riser of 7 3/4 in. and minimum tread of 10 in. follow IRC R311.7. The comfort check (twice the riser plus the tread between 24 and 25.5 in.) is a layout convention, not a code requirement.
• Rebar. Bar numbers, nominal diameters, weights per foot, and areas follow the standard ASTM A615 size table. Lap length uses 40 bar diameters as a rule of thumb. The structural drawings set the real lap length.
• Concrete. Volume is cubic feet divided by 27. Bag yields are 0.45 cubic feet for a 60 lb bag and 0.60 cubic feet for an 80 lb bag. Weight uses 4,050 lb per cubic yard, a typical figure for normal-weight concrete.
• Roofing. One square covers 100 square feet. The slope multiplier is the square root of 1 plus the squared rise per foot of run. Standard asphalt shingles are counted at 3 bundles per square, and bundle coverage varies by product.
• Drywall. Board counts come from area and sheet size. Tape, joint compound, and screws use published estimating factors per 1,000 square feet of board.
• Masonry. Unit counts use nominal dimensions: modular brick and 8 by 8 by 16 in. CMU, including the mortar joint.
• Waste. Percentages are common planning allowances. They are not standards, and the waste guide lists what raises them.

Known limits

The calculators produce planning estimates. Use them to price a job, order materials, or check a layout before you cut. They do not replace the structural drawings, the manufacturer's installation instructions, or the local building department.

• Adopted code editions and local amendments differ. A limit quoted from the IRC may be stricter where you build.
• Joint compound and tape use depends on finish level and technique. Treat those figures as averages.
• Concrete orders depend on subgrade, formwork accuracy, and the supplier's load rules. The calculator does not know any of these.
• Waste percentages assume a typical layout. Diagonal patterns, many offcuts, and lot-matched products raise them.

Editorial standards

• A code section or limit is stated only when it can be checked against the published code text.
• Rules of thumb are labeled as rules of thumb, with the basis given.
• Guides do not claim field testing, certifications, or experience that the site cannot document.
• Guide tables that show calculator output are generated from the calculation functions. Tables of code limits are typed by hand and checked against the published text.
• Advertising is served by Google AdSense. It is separate from the content and does not change any calculator result. The site has no affiliate links and no sponsored placements.

Corrections

Send the page address, the inputs you used, the result you expected, and a source if you have one to [email protected]. A correction that includes a source is checked first. When a number is wrong, the function is fixed, the guides that use it are regenerated, and the change is added to the log below with its date.

Change log

• October 3, 2026. Named the site operator, WayPoint, on the About, Privacy, Terms, and Contact pages and in the site footer.
• October 2, 2026. Published the guides section: eight reference articles and an index, each linked to its calculator.
• October 2, 2026. Corrected the drywall calculator. Joint compound dropped from 0.053 to 0.01 gallons per square foot, and joint tape from 1.4 to 0.37 linear feet per square foot. The earlier factors overstated both by a wide margin when compared with published estimating figures per 1,000 square feet of board. The screw count for 4x10 and 4x12 sheets now scales with sheet area. It had used the 4x8 count per sheet, which understated screws for the larger sheets.
• October 2, 2026. Fixed a rounding error in the concrete, drywall, brick and block, roof pitch, and roofing square calculators. A quantity that should land exactly on a whole number could round up to the next unit because of floating-point noise. For example, 52.8 cubic feet of concrete in 80 lb bags showed 89 bags instead of 88.
• October 2, 2026. Removed the "0ms" speed claims from page headings. Results update as you type, but the site does not publish a latency figure.

Guides

• Concrete Yardage Chart: Slab Volume, Bags, and Truck Loads
• Rebar Size and Weight Chart (#3 to #11) with Lap and Cover Rules
• IRC Stair Requirements: Rise, Run, Headroom, and Handrails Explained
• Roof Pitch Chart: Angle, Slope Multiplier, and Rafter Length per Foot of Run
• How Much Drywall to Order: Sheets, Screws, Tape, and Joint Compound
• Roofing Squares and Bundles: How to Order Shingles for Any Roof
• Brick and CMU Block Quantities per 100 Square Feet of Wall
• Construction Waste Factors by Material: What to Add and When

See also the privacy policy, the terms and disclaimer, and the contact page.