FramingCalcs
Free calculators for rafters, hips, roof pitch, framing layout and material takeoff, each showing the geometry or standard behind the answer.
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Framing & Roof Geometry
Rafter geometry, wall takeoffs and roof pitch conversion, with the ridge shortening and actual lumber dimensions built in.
- Rafter Length Calculator Calculate common rafter length from span and pitch, including ridge shortening and overhang measured along the slope — the two adjustments most calculators skip.
- Hip Rafter Calculator Hip rafter length from span and pitch, with the 16.97 unit run, backing bevel angle, hip drop, ridge shortening and the jack rafter common difference.
- Roof Pitch Calculator Convert roof pitch between rise-over-12, degrees and percent, and see which roof coverings that slope allows under the IRC.
- Stud Count Calculator Count studs for a wall including corners, wall intersections and door or window framing — not just length divided by spacing.
- Deck Board Calculator Count deck boards using actual board widths and gap spacing, with joist count, linear feet and fastener quantities.
- Gable Stud Calculator Gable end stud lengths from building width, pitch and spacing, with the fixed step between studs and the single bevel angle that cuts all of them.
- Board Foot Calculator Calculate board feet and cost from thickness, width and length, and see how much of the wood you are billed for was removed at the mill.
- Drywall Calculator Count drywall sheets, screws, tape and compound from room dimensions, and see how sheet length and hanging direction change the number of butt joints.
- Crown Molding Angle Calculator Compound miter and bevel settings for crown molding from spring angle and the actual corner angle, plus the simpler nested method that needs no bevel.
- Tile Layout Calculator Work out edge cut widths for a tile floor, compare a centred layout against starting at a wall, and see when to shift the grid half a tile.
- Wood Movement Calculator Calculate how much a board moves across its width with seasonal humidity change, by species and by whether it is flatsawn or quartersawn.
Roofing & Cladding
Material takeoff from footprint and pitch, with waste scaled to how complex the roof actually is.
- Roofing Material Calculator Calculate shingle bundles, underlayment, ridge cap and drip edge from building footprint and pitch, with waste scaled to roof complexity.
- Attic Ventilation Calculator Work out attic ventilation net free area under IRC R806.2, check whether you qualify for the 1/300 ratio, and balance ridge against soffit venting.
- Lap Siding Calculator Work out lap siding exposure, course count and linear feet from wall height and board width, and set the courses to land on window heads.
Footings & Concrete
The load a beam, post or footing actually carries — half the span each side, not the whole of it — and concrete volume with a straight answer on bags versus ready-mix. Member sizing is not published here; see the methodology page.
- Tributary Load Calculator Work out the tributary area and load carried by a beam, bearing wall, post or footing, using half the span on each side rather than the full span.
- Concrete Calculator Calculate concrete volume for slabs, footings and round columns in cubic yards and bags — and find out when bagged mix stops making sense.
Every answer names its source
There is no shortage of calculators on the web. What is scarce is one that tells you where its number came from, so you can check it. Every result on this site names the formula, standard or manufacturer figure behind it on the line that produced it, rather than in a footnote.
That is not decoration. A front axle result that says 278 lb lighter than unhitched, from tongue weight × overhang ÷ wheelbase can be checked on a scale, argued with, or used to decide where the load goes. One that says within limits cannot be checked at all.
Built to answer the whole question
Most calculators solve half a problem and stop. A towing calculator that reports GCWR but ignores payload will call an overloaded truck legal. A water heater tool that goes by tank gallons misses that a smaller tank with a stronger burner delivers more hot water. A tankless unit rated at five gallons a minute delivers under three in a northern winter, with nothing wrong with it.
Each of the 16 calculators here applies every constraint that governs its answer, and says which one is binding. Where an assumption is deliberately left out — Manual J, NPSH, engineered spans — the page says so plainly rather than letting you assume it was included. Tools whose answer would be safety-critical if it were wrong are not published here; the methodology page explains which, and why.
One source of truth
The 4 reference charts are generated from the same data the calculators run on. The pump head calculator imports its friction loss from the pipe size calculator rather than keeping a second copy. Two pages on this site cannot disagree about the same question, because there is only one answer in the code.
The calculations are covered by an automated test suite that runs before anything is published, and some of those tests deliberately assert the behaviour that makes each tool useful. More on how that works on the methodology page.
What these tools are not
They are estimates for planning. They are not engineered designs, permit documents or a substitute for a licensed professional. Codes carry local amendments, editions change, and the authority having jurisdiction in your area has the final say. Every calculator carries a disclaimer describing exactly what it does not model — those are worth reading before you rely on a result.