36 calculators
Construction calculators
Concrete, framing, roofing, decks, drywall, tile and landscape materials.
Worked example10 × 12 ft slab, 4 in thick = 1.48 yd³ of concrete before waste
Free tools for the job site and the workshop
Construction and woodworking calculators, charts and guides
70 calculators, a 192-species wood database and thread charts. Every tool shows its formula and its sources.
Browse by category
Six sections, each with its own calculators, data tables and reference pages.
34 calculators
Woodworking and shop math
Board feet, cut lists, wood movement, joinery layout and machine speeds.
Worked exampleA 1 × 6 board, 8 ft long = 4 board feet (nominal)
192 woods
Wood species data
Hardness, weight, strength and shrinkage from the USDA Wood Handbook.
From the dataNorthern red oak: 1,290 lbf Janka hardness at 12% moisture
34 charts
Thread, tap and fastener charts
Tap drills, thread pitches, clearance and pilot holes, torque and wrench sizes.
From the chart1/4-20 tap: #7 drill, 75% thread
35 guides
Building code guides
IRC, OSHA and ADA rules in plain language, plus ventilation, energy and material size guides.
From the guideADA ramps: steepest running slope 1:12 (8.33%)
Joinery, tools, projects
Guides and projects
How-to guides for joints, tools and wood choice, plus project ideas.
Inside18 wood joints explained, from butt joints to dovetails
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Browse everything: calculators, wood species, thread charts, code guides
How we check the numbers
These are planning and estimating tools. For anything structural or safety-related, confirm with your local building department.
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Formula on every page
Each calculator explains its method on the page and lists its sources, so you can check the arithmetic.
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Tested against published answers
The calculation code runs known-answer tests against figures from the sources. A page is not published while a test fails.
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Public reference data
USDA Forest Products Laboratory Wood Handbook, ASTM and ASME standards, OSHA rules and the 2010 ADA Standards, cited where used.
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Corrections
When we find a mistake we fix it on the same page and update its “Last reviewed” date. Spot one? Tell us.
Methodology and correctionsAbout BuilderologyReport an errorDisclaimer
Recently added
New calculators, charts and guides, with the date each was published.
More guides
Reference posts, business help and wood and materials guides.