Trade calculators & tools
Free calculators and lookups for every trade — plumbing, electrical, HVAC, concrete and more. No sign-up. Filter by trade, what it does, or who it's for.
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Water heater size
What size water heater do I need? Pick people + fuel, get the size.
Open tool →First hour rating calculator
What is your water heater's First Hour Rating? Enter the tank size, heat input and temperature rise — get the hot water it delivers in the first hour (usable storage + recovery).
Open tool →Drain slope / fall
Total drop over a run, with the code-minimum slope cited for your area.
Open tool →Tankless water heater size
Flow rate (GPM/Lpm) and temperature rise for an on-demand heater.
In the worksWater softener size
What size water softener do I need? Enter your household size, water hardness and daily use — get the grain capacity to look for, sized to regenerate about once a week.
Open tool →Pipe offset calculator
How long do you cut a pipe offset? Enter the offset and pick the fitting angle — get the travel (the diagonal to cut) and run, with the 45° 1.414 multiplier and rolling offsets built in.
Open tool →Expansion tank sizing calculator
What size expansion tank do you need? Enter the water heater or system volume, the temperatures and the fill and relief pressures — get the minimum thermal expansion tank size in gallons or litres.
Open tool →Sump pump sizing calculator
What size sump pump do you need? Do the one-minute pit test — enter the pit diameter and how far the water rises in a minute — and get the gallons-per-hour (or litres-per-hour) capacity your pump must deliver at your lift.
Open tool →Concrete calculator
How much concrete do I need? Enter length, width and thickness — get cubic yards, metres and bags.
Open tool →Concrete footing calculator
How much concrete do I need for footings or post holes? Enter the shape, dimensions and number of footings — get cubic yards, cubic feet or cubic metres plus the bag count.
Open tool →Cylinder volume calculator
What is the volume of a cylinder? Enter the diameter and height — get the volume in cubic feet, cubic yards, gallons and litres, using V = π r² h, for upright or on-its-side tanks and partial fills.
Open tool →Pool volume calculator
How many gallons is my pool? Enter the shape and dimensions — get US gallons and litres for rectangle, round, oval and kidney pools.
Open tool →Slope calculator
What is the slope? Enter rise and run — get the percent grade, the angle in degrees and the ratio (1 in n), plus the length along the slope. For ramps, driveways, drainage falls and land grading.
Open tool →Gravel calculator
How much gravel do I need? Enter length, width and depth — get tons, cubic yards and tonnes for gravel, road base or sand.
Open tool →Asphalt calculator
How much asphalt do I need? Enter length, width and thickness — get the tons (and tonnes) of hot-mix asphalt to order for a driveway, path or car park.
Open tool →Board foot calculator
How many board feet do you have? Enter thickness, width, length and quantity — get the total board footage of lumber, plus the volume in cubic feet or metres.
Open tool →Drywall calculator
How much drywall do I need? Enter your room size and sheet size — get the number of sheets to buy, plus a screw estimate, for walls and ceilings.
Open tool →Tile calculator
How many tiles do I need? Enter the area and your tile size — get the number of tiles (and boxes) to buy for a floor or wall, with a waste allowance for cuts.
Open tool →Flooring calculator
How much flooring do I need? Enter the room size and your box coverage — get the area to buy and the number of boxes for laminate, vinyl plank, hardwood or engineered floors, with a waste allowance worked in.
Open tool →Fence calculator
How many fence panels do I need? Enter your fence length and panel width — get the panel count and posts. Switch to picket mode for posts, rails and individual pickets.
Open tool →Sod calculator
How much sod do I need? Enter your lawn length and width — get the area, square yards, pieces and how many pallets to order for a new lawn.
Open tool →Mulch calculator
How much mulch do I need? Enter your bed size and depth — get the cubic yards (or cubic metres) and the number of bags to buy for garden beds and borders.
Open tool →Paver calculator
How many pavers do I need? Enter the area length, width and paver size — get the count instantly, with a waste allowance for cuts and breakage.
Open tool →Topsoil calculator
How much topsoil do I need? Enter the area length, width and fill depth — get cubic yards, cubic metres and bag count instantly.
Open tool →Sand calculator
How much sand do I need? Enter length, width and depth — get cubic yards (or cubic metres), weight in tons, and the number of bags to buy instantly.
Open tool →Plywood calculator
How many sheets of plywood do I need? Enter the area and pick your sheet size — get the sheet count instantly, with a waste allowance for cuts.
Open tool →Wallpaper calculator
How many rolls of wallpaper do I need? Enter your room size, wall height and roll size — get the rolls to buy, worked out by counting full-height drops with the pattern repeat allowed for.
Open tool →Paint calculator
How much paint do I need? Enter your room size, coats and coverage — get the gallons or litres to buy, with doors and windows deducted and your tin's spread rate allowed for.
Open tool →Brick calculator
How many bricks do I need? Enter the wall size and your brick size — get the number of bricks to buy for a single- or double-skin wall, with the mortar joint and a waste allowance worked in.
Open tool →Retaining wall calculator
How many blocks do I need for a retaining wall? Enter the wall size and your block size — get the blocks, courses, caps and base gravel to order, with a waste allowance.
Open tool →Deck calculator
How many deck boards do I need? Enter the deck size, board and gap — get the boards, rows, lineal length and screws to order, with a waste allowance.
Open tool →Roof pitch calculator
Enter rise and run — get the pitch (x:12), the roof angle, grade %, slope factor and rafter length.
Open tool →Roofing calculator
How much roofing do I need? Enter your roof footprint and pitch — get the area, the roofing squares and how many bundles of shingles to order.
Open tool →Stair calculator
Enter your floor-to-floor rise — get the number of risers, riser height, run, stringer length and angle.
Open tool →BTU calculator
How many BTUs do I need? Enter your floor area, ceiling height and climate — get the air conditioner or heater size in BTU/hr, kW and tons, using the standard sizing rules of thumb.
Open tool →Solar panel calculator
How many solar panels do I need? Enter your monthly kWh, peak sun hours and panel wattage — get the system size in kW and the number of panels to fit.
Open tool →Framing calculator
How many studs do I need? Enter the wall length, stud spacing, corners and openings — get the stud count plus the plate lumber for the wall.
Open tool →Insulation calculator
How much insulation do I need? Enter the wall or attic size and your package coverage — get the area to buy and the number of rolls, batt packs or bags, with a waste allowance worked in.
Open tool →R-value calculator
What is the R-value of your wall, roof or floor? Add each material layer and its thickness — get the total R-value, RSI and U-value, for insulation, walls and attics.
Open tool →Voltage drop calculator
Will my wire drop too much voltage? Enter the current, run length and wire size — get the % drop checked against the 3% / 5% guideline, in AWG or mm², copper or aluminium.
Open tool →Wire size calculator
Can I run 14 gauge wire on a 20 amp circuit? Pick your wire gauge, breaker size and conductor — get an instant safe/not-safe check against NEC Table 310.16 ampacity.
Open tool →Joist & rafter span calculator
What is the maximum span of a 2x10 joist? Pick species, spacing and dead load — get the max span for common floor joists and roof rafters, per IRC span tables.
Open tool →Pipe volume / capacity
Litres or gallons held in a length of pipe, by diameter.
Open tool →Pipe water velocity
How fast is the water moving in your pipe? Enter the flow rate and inside diameter — get the velocity in ft/s or m/s, checked against the usual design guideline.
Open tool →Pipe friction loss calculator
How much pressure does your pipe run lose to friction? Enter the flow, inside diameter, length and material — get the head loss and pressure drop, using the Hazen-Williams equation.
Open tool →Pipe weight calculator
How much does your pipe weigh? Enter the outside diameter, wall thickness, length and material — get the weight in pounds or kilograms, empty and full of water.
Open tool →Water usage calculator
How much water does your household use? Enter your people, fixtures and habits — get your water use per day, month and year, with a breakdown of where it goes.
Open tool →Pump head calculator
How much head does your pump need? Enter the static lift, the pipe friction loss and any required outlet pressure — get the total dynamic head (TDH) in feet or metres, ready to read off a pump curve.
Open tool →GPM / flow rate
Measure your water flow rate — time a container filling, get gallons per minute.
Open tool →Plumbing unit converter
mm↔inch, bar↔psi, °C↔°F, L/min↔GPM, L↔gal, m²↔ft² — instant, both ways.
Open tool →Drain pipe size (DFU)
Add up fixtures, get the minimum drain pipe size for your code.
In the worksWater heater / repipe cost
Realistic cost range for a replacement or repipe in your area.
In the worksPipe freeze risk
When will your pipes freeze, and what insulation prevents it.
In the worksGenerator size calculator
What size generator do I need? Select the appliances you want to run — get the running load, starting-demand peak and the recommended generator size instantly.
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