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35 free working calculators, grouped by trade. Open a tool, enter your measurements and review the formula and assumptions beside the result.
35 of 35 calculators shown
Electrical
6 toolsVoltage Drop Calculator
Calculate voltage drop, percent loss and load voltage for AC, DC and three-phase circuits.
Open calculator →Wire Size Calculator
Estimate a copper or aluminum AWG candidate from voltage, current, one-way distance and a voltage-drop target.
Open calculator →Watts to Amps Calculator
Convert real electrical power in watts to estimated current in amps across DC, single-phase, and balanced three-phase circuits.
Open calculator →Amps to Watts Calculator
Convert electrical current in amps to real power in watts using circuit voltage, power factor, and DC, single-phase, or three-phase mode.
Open calculator →kVA to Amps Calculator
Convert apparent power in kilovolt-amperes (kVA) to load current in amps for single-phase and balanced three-phase US electrical systems.
Open calculator →Conduit Fill Calculator
Calculate NEC conduit fill percentage, allowable wire count, and raceway capacity for EMT and Schedule 40 PVC with THHN copper conductors.
Open calculator →Concrete & Masonry
12 toolsConcrete Calculator
Calculate concrete volume in cubic yards and 80 lb bags for slabs, pads and rectangular footings.
Open calculator →Concrete Bag Calculator
Calculate how many 40, 50, 60 or 80 lb bags of concrete a rectangular project needs.
Open calculator →Concrete Block Calculator
Estimate nominal concrete masonry unit count from wall dimensions, openings, block face size and waste allowance.
Open calculator →Concrete Footing Calculator
Calculate concrete volume in cubic feet and cubic yards for continuous rectangular footings using total length, width, depth, and waste.
Open calculator →Post Hole Concrete Calculator
Estimate concrete volume and 40 to 80 lb bag counts for round post holes in feet and inches, automatically subtracting buried post displacement.
Open calculator →Concrete Wall Calculator
Estimate poured concrete wall volume in cubic yards and cubic feet while subtracting window and door openings and adding order allowance.
Open calculator →Concrete Column Calculator
Calculate cubic feet and cubic yards for identical round concrete columns or Sonotube piers using diameter, height, count, and allowance.
Open calculator →Concrete Weight Calculator
Convert concrete volume in cubic yards to estimated weight in pounds and US short tons using your chosen concrete unit density.
Open calculator →Gravel Calculator
Calculate gravel, crushed stone, or pea gravel needed in tons and cubic yards from project length, width, depth, and waste allowance.
Open calculator →Rebar Calculator
Calculate rebar grid lines, lap splices, total linear feet, 20 ft stock bar counts, and steel weight for concrete slabs.
Open calculator →Paver Calculator
Calculate patio pavers, 4-inch gravel base, bedding sand, edge restraints, and cutting waste for patios and walkways.
Open calculator →Mulch Calculator
Calculate landscaping mulch, topsoil, and garden bed depth in cubic yards, cubic feet, 2 cu ft and 3 cu ft retail bags, and bulk truckloads.
Open calculator →Roofing
6 toolsRoofing Calculator
Calculate roof area, roofing squares, shingle waste and material cost from pitch.
Open calculator →Roof Pitch Calculator
Calculate roof pitch in degrees, slope multiplier and rafter length from rise per 12.
Open calculator →Metal Roofing Calculator
Estimate panel count and sloped panel length for one rectangular metal-roof plane from pitch and effective coverage width.
Open calculator →Roof Shingle Calculator
Convert measured sloped roof area into whole shingle bundles and roofing squares using product bundle coverage and waste allowance.
Open calculator →Roof Underlayment Calculator
Estimate synthetic or felt roofing underlayment roll counts from measured sloped roof area, lap allowance, and installed roll coverage.
Open calculator →Ridge Cap Calculator
Estimate hip and ridge cap shingle bundles from combined linear ridge and hip footage, cutting waste, and product coverage per bundle.
Open calculator →Carpentry & Framing
8 toolsStair Calculator
Calculate stair rise and run, riser count, tread count, riser height and angle.
Open calculator →Stair Stringer Calculator
Calculate stair stringer length, stock-board length, angle and estimated stringer count.
Open calculator →Board Foot Calculator
Calculate total and per-piece board feet from nominal or actual lumber thickness, width, length, and piece count for US timber estimates.
Open calculator →Plywood Sheet Calculator
Estimate whole 4×8 plywood or OSB subfloor and sheathing sheet counts from measured surface area, sheet dimensions, and cutting waste.
Open calculator →Rafter Length Calculator
Estimate common rafter slope length and framing stock length from building span, ridge thickness, roof pitch, and horizontal overhang.
Open calculator →Drywall Calculator
Calculate 4x8 and 4x12 drywall sheet counts, joint compound, screws, and tape from room dimensions, ceiling height, and openings.
Open calculator →Wall Stud Calculator
Calculate 2x4 and 2x6 wall studs, 16 or 24 inch on-center spacing, corner posts, and top/bottom plate lumber with waste allowance.
Open calculator →Fence Calculator
Calculate fence posts, 2x4 horizontal rails, dog-ear pickets, post-hole concrete bags, and gate hardware for privacy and picket fences.
Open calculator →Measurement
3 toolsSquare Footage Calculator
Calculate the square footage of a room from feet and inches, with square yards included.
Open calculator →Tile Calculator
Calculate floor and wall tile square footage, full retail boxes to purchase, cutting waste allowance, and grout bag requirements.
Open calculator →Paint Calculator
Calculate interior wall and ceiling paint, doors and window deductions, coats, gallons and quarts to buy, and primer.
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