Construction calculators that show their work
Construction and architectural calculators that cite their constants, handle imperial and metric properly, and flag the cases where the arithmetic is right but the answer will not survive an inspection.
Drawing & measurement
- Architectural Scale ConverterConvert between drawing scale and real size at any imperial, engineering or metric scale. Feet-inches to the nearest 1/16 inch, with the rounding residual shown.
- Area Unit Converter — m², ft², pyeong, tsuboConvert square metres, square feet, Korean pyeong, Japanese tsubo, acres and hectares through exact legal definitions rather than rounded factors.
- Slope and Grade CalculatorConvert slope between percent, ratio, degrees and fall over a run, and see the fall for any run length.
Structure & layout
- Stair Rise and Run Calculator — IBC and IRC checkRiser height, tread depth, total run and stringer length from a total rise, checked against IBC 1011.5 and IRC R311.7 limits, which are not the same.
- Roof Pitch ConverterConvert roof pitch between rise-per-12, degrees, percent and rafter multiplier, and get rafter length for any run.
- Wall Framing Calculator — studs and platesStud count, plate footage and framing factor, with a direct comparison of 16 and 24 inch on-centre spacing.
- Assembly R-Value Calculator — nominal vs effectiveSee what a framed wall actually delivers once the studs bridge the insulation, using the parallel path method with a framing factor.
Materials & quantities
- Concrete Volume CalculatorConcrete volume for a slab, footing or column in cubic yards and cubic metres, with a realistic waste factor and bag counts from published yields.
- Rebar Calculator — bars, laps and spacing checkBar count and weight for a slab, including the lap splices most calculators omit and a check against the ACI 318 maximum spacing.
- Tile and Flooring CalculatorTiles, boxes and attic stock for a room, with a waste allowance sized to the lay pattern.
- Board Feet Calculator — nominal vs actualBoard feet, linear feet and cost for framing lumber, showing both the nominal size you are billed for and the actual surfaced size you build with.
- Drywall CalculatorSheets, screws, tape and joint compound for a room, plus a comparison of board lengths and the joints each one leaves you.
- Paint Coverage CalculatorWall area minus openings, times the number of coats, rounded up to whole cans — and how much is left for touch-ups.
- Roofing Calculator — squares, bundles and pitch areaRoofing squares and shingle bundles from a building footprint, with the pitch multiplier that makes a roof larger than the house beneath it.
- Concrete Block (CMU) CalculatorBlock count, courses, mortar and grout for a concrete block wall, with the exact blocks-per-square-foot arithmetic shown.
Site & groundwork
- Excavation Calculator — swell, haul and backfillBank, loose and compacted volumes for an excavation: how much you dig, how much you haul, and why the hole will not fill itself.
- Gravel and Aggregate CalculatorAggregate volume and tonnage for a driveway or base course, with a compaction allowance and the density caveat that decides whether a delivery arrives short.
- Retaining Wall Calculator — blocks, base and drainageBlock count, buried base course and drainage stone for a retaining wall, with the height at which engineering and permits enter the picture.
- Fence Post Concrete CalculatorConcrete per post hole and total bags for a fence, with embedment depth checked against the one-third rule and a frost depth warning.
- Mulch and Topsoil CalculatorCubic yards and bags of mulch, topsoil or compost for a bed, plus guidance on the depth that actually helps.
- Deck Board CalculatorDeck boards, joists and fasteners, with the installation gap that differs between wet treated lumber and pre-dried or composite boards.