Free calculators, unit converters, and reference guides for construction and home renovation. No sign-up required.
Convert lengths, areas, volumes, weights, and more.
12 tools 🧮Estimate paint, tile, concrete, and other materials.
27 tools ⚡Wire sizing, circuit breakers, lighting calculators.
10 tools 🔥Boiler, radiator, and pipe sizing tools.
6 tools 📐Room area, stairs, roof pitch, and squareness checks.
9 tools 📋Standard sizes, codes, and material references.
17 toolsCalculate aerated concrete (AAC) blocks needed for a wall based on wall area, block dimensions, and mortar joint.
Open →Convert between degrees, radians, percent slope, and ratio (run:rise). Useful for roof pitches, ramps, and grading.
Open →Convert area between metric and imperial units: square metres, square feet, square inches, acres, and hectares.
Open →Work out how many baseboard or skirting pieces to buy from the room perimeter, minus doors, with an allowance for corner cuts and the finish nails into studs.
Open →Estimate the boiler power in kW you need from floor area, ceiling height, insulation level, and climate zone, with a heat-load breakdown.
Open →Calculate bricks needed for a wall based on wall area, brick size, and mortar joint thickness. Standard sizes supported.
Open →Find the BTU/h a room air conditioner needs from floor area, using the ENERGY STAR chart with sun, occupant and kitchen adjustments. Cooling only.
Open →Work out how much carpet to buy in square yards or m² from room size and roll width, with the length to cut, number of strips, seams and underlay.
Open →Pick the correct circuit breaker for a given continuous load, with NEC 80% rule and IEC adjustments. Supports general, dedicated, and motor circuits.
Open →How many 8×16 concrete blocks a wall needs, plus 80 lb bags of mortar and of core-fill grout for a fully grouted wall, from CMHA and manufacturer data.
Open →Calculate concrete volume and mix quantities — cement, sand, and gravel — for slabs, strip footings, and columns, using standard mix ratios.
Open →How long concrete takes to cure at your temperature: when you can walk on it, strip forms, drive on it and when it reaches full strength at 28 days.
Open →Concrete strength classes to EN 206 with cylinder and cube strength (MPa), psi, IS 456 nominal mixes and typical uses, from C12/15 to C50/60.
Open →Check conduit fill for THHN wire in EMT or PVC against the NEC 40% rule and find the most wires of each size a conduit can hold, with the full chart.
Open →Calculate how many decking boards, joists, and screws you need from your deck size, board width, gap, and joist spacing.
Open →Typical widths, heights, and thicknesses for residential doors in the US, UK, and EU, covering both interior and exterior door openings.
Open →Find the right drill bit for any screw size in softwood, hardwood, masonry, or sheet metal, including wall plug sizes and clearance holes.
Open →Calculate drywall sheets needed for a wall of given dimensions, plus the metal profiles, screws, and joint tape required to finish it.
Open →Find the right drywall anchor for a given weight. Safe working loads for plastic, self-drilling, molly, toggle and strap anchors in 1/2 in and 5/8 in board.
Open →Convert energy between joules, kilojoules, kilowatt-hours, kilocalories, and BTU. Exact factors for engineering and cooking contexts.
Open →Calculate how much your appliance costs per month and per year based on power, usage hours, and electricity tariff.
Open →Calculate posts, pickets, rails, and post length for a wood or composite fence, with gate deduction and spacing between posts.
Open →Calculate how much concrete you need to set fence posts, including the volume per hole and the number of 25 kg post-mix bags.
Open →Convert fractional inches to decimals and millimetres, and millimetres back to the nearest 1/8, 1/16, 1/32, or 1/64 inch.
Open →Typical frost depth for the US, Canada, UK, and Europe — used for footing depth and buried water-line placement.
Open →What size generator you need: add running watts of your appliances plus the largest starting surge, with central AC sizing and CO and backfeed safety.
Open →Glossary of common construction, renovation, and trade terms — framing, materials, finishes, electrical, and plumbing. Clear definitions with categories.
Open →Work out how many tonnes, cubic metres, cubic yards, and bulk bags of gravel or crushed stone you need for a driveway, path, or base layer.
Open →Calculate how much tile grout you need from your tiled area, tile size, joint width, and tile thickness, in kilograms and bags.
Open →Find how many boxes of hardwood flooring to buy, with the waste allowance for straight, diagonal or herringbone layouts and the cleats or glue you need.
Open →Calculate insulation packs needed (mineral wool, EPS, XPS, PIR) for walls, roofs, or floors, with R-value estimates.
Open →Calculate how many laminate or parquet boards and packs you need for a floor, including a waste allowance for cuts and pattern matching.
Open →Convert lengths between metric and imperial units: metres, centimetres, millimetres, kilometres, inches, feet, yards, miles.
Open →Calculate lumens and watts needed to light a room based on area, room type, and source efficacy (LED, CFL, halogen, incandescent).
Open →Work out how many metres of linoleum or vinyl sheet to buy from room length, width and roll width, with strips, seams and a trim allowance.
Open →Calculate board feet and cubic metres from lumber piece dimensions, or work backwards to find piece counts from a volume budget.
Open →Actual milled dimensions for nominal lumber sizes. See what a 2x4, 2x6, or 1x8 really measures, in inches and millimetres.
Open →Calculate the cement and sand needed for laying brick or block, using standard mortar mix ratios of 1:3, 1:4, and 1:6, in kg and bags.
Open →How much mulch, topsoil or compost to order: cubic yards and cubic metres, number of bags, a weight range by material and recommended depths.
Open →What 16d, 10d and 8d nails actually measure. Penny sizes with length in inches and millimetres, gauge and shank diameter, plus the nail to use for each job.
Open →Solve Ohm's law for voltage, current, resistance, or power. Enter any two known values and get the rest, including the power dissipated.
Open →Estimate how much paint you need based on wall area, number of coats, and coverage. Get litres needed plus can counts.
Open →Paint sheens compared by gloss units — MPI levels, EN 13300 classes and brand data sheets — with the finish paint makers recommend for each room.
Open →Find the required pipe inside diameter from flow rate and water service, then pick the smallest copper type L or M tube and see its actual velocity.
Open →Minimum fall for a horizontal drain by pipe size and code — IPC, IRC, UPC or UK Approved Document H — as inches per foot, mm per metre, percent and 1:N.
Open →What nominal pipe sizes really measure. NPS to DN, outside diameter in inches and millimetres, Schedule 40 and 80 wall thickness and the resulting bore.
Open →Calculate the plaster you need for a wall, in kilograms and bags, from the wall area and the coat thickness you plan to apply.
Open →Convert power between watts, kilowatts, megawatts, horsepower, and BTU/h. Useful for engines, heaters, and appliances.
Open →Convert pressure between bar, PSI, pascal, kilopascal, megapascal, atmosphere, and mmHg using exact conversion factors.
Open →Calculate primer needed for walls, accounting for coats, coverage, and surface absorbency (smooth, textured, porous).
Open →Calculate the weight of putty or spackle needed to fill and smooth walls before painting, from the wall area and layer thickness.
Open →Calculate the number of radiator sections needed for a room based on volume, insulation, climate, and section heat output.
Open →Common rafter length from building span and roof pitch, with the ridge board deduction, overhang tail, roof angle and the plumb and seat cut angles.
Open →Work out ramp run and total length from the rise at a 1:12, 1:15 or 1:20 slope, including the landings ADA requires and whether handrails are needed.
Open →Steel reinforcement bar sizes: US imperial (#3, #4, #5, #6, #8) and metric (⌀8–⌀25 mm) with diameter, mass per metre, and cross-section area.
Open →Decode resistor colour bands into resistance and tolerance. Supports 4-band and 5-band resistors with the full IEC 60062 colour table.
Open →Calculate roof pitch from rise and run, degrees, or ratio. Get pitch in degrees, percent slope, ratio, and rafter length.
Open →Calculate roof area with eave and gable overhangs for gable, hip or flat roofs, then metal sheets by effective width or bitumen shingle packs.
Open →Calculate the floor area of rectangular or L-shaped rooms in square metres, with optional deductions for windows and door openings.
Open →Convert sandpaper grit between US CAMI and European P grades, see grain size in microns and pick the grit for drywall, bare wood, paint and polishing.
Open →Calculate how many vinyl or wood siding panels and boxes you need for an exterior wall, including a waste allowance for cuts.
Open →Convert speed between metric and imperial units: kilometres per hour, mph, metres per second, knots, and feet per second.
Open →Check if a corner is square using the 3-4-5 method. Enter two sides and the measured diagonal to see the exact expected value and deviation.
Open →Calculate the number of steps, exact riser height, tread depth, and incline angle for a staircase between two floors. Includes code-compliance check.
Open →Typical stud spacing for residential and commercial framing in the US, UK, Canada, and Europe. Imperial and metric values, use cases, and exceptions.
Open →Convert temperature between Celsius (°C), Fahrenheit (°F), and Kelvin (K). Exact formulas, instant conversion.
Open →Calculate how many tiles you need for a floor or wall from your area and tile size, including a waste allowance for cuts and breakage.
Open →Calculate how many kilograms and bags of tile adhesive you need from your tiled area and the notched trowel size you will use.
Open →Convert torque between newton metres, foot-pounds, inch-pounds and kgf·m, with the remaining units shown alongside. Includes typical tightening torques.
Open →Find the height to mount a TV so the centre of the screen sits at eye level, with the bottom and top edges, screen size and the viewing distance to aim for.
Open →Estimate pipe length, heat output, and number of circuits for wet underfloor heating. Supports bathroom, kitchen, living, bedroom room types.
Open →Calculate voltage drop across a wire run based on length, current, gauge, and system voltage. Checks against the 3% recommended limit.
Open →Convert volume between metric and imperial units: litres, millilitres, cubic metres, cubic feet, US and UK gallons, quarts, and pints.
Open →Calculate total wall area, then subtract windows and doors to get the net paintable or wallpaperable area of the room.
Open →Typical thicknesses and layer breakdowns for drywall, brick, cavity, metal stud, and concrete walls, plus guidance on drilling safely.
Open →Calculate how many wallpaper rolls you need for a room, accounting for pattern repeat, roll size, and a waste allowance.
Open →Convert watts to amps and amps to watts for DC, single-phase, and three-phase supplies, including power factor and apparent power in VA.
Open →Convert weight and mass between metric and imperial units: kilograms, grams, pounds, ounces, metric tons, and US short tons.
Open →Typical widths and heights for residential windows in the US (double-hung, casement, picture), UK (casement, sash), and EU (tilt-turn).
Open →Electrical wire color codes for US residential and commercial, EU IEC, and UK (post-2004 vs legacy). Hot, neutral, ground identification.
Open →Pick the right wire size (AWG or mm²) for your circuit based on current load and the number of conductors in the raceway. Based on NEC and IEC ampacity tables.
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