Construction calculators
Construction and DIY calculators for materials, dimensions, and costs. Concrete, flooring, roofing, brickwork — sized correctly so you buy the right amount.
19 calculators
- AC Tonnage Calculator
Estimate the central air-conditioning size your home needs. Enter conditioned square footage, climate zone and a few envelope details, and get the cooling load in BTU/hr and the recommended unit size in tons.
- Asphalt Calculator
Enter your paving area dimensions and we work out the asphalt tonnage, volume (m³ and yd³), and total cost based on the standard hot-mix density.
- Beam Deflection Calculator
Estimate the maximum deflection and bending moment of a prismatic beam. Pick the support and load case, set the span, load, Young's modulus and second moment of area, and the calculator returns the textbook closed-form answer.
- Board Foot Calculator
Enter the nominal thickness, width and length of a piece of lumber — we calculate the board feet per piece, the total board feet for the order, and the cost at your lumber yard price.
- Boiler Size Calculator
Estimate the right kW output for a new boiler from your floor area, insulation level, boiler type and number of bathrooms — the same rule of thumb used by Energy Saving Trust and the major UK boiler manufacturers.
- Brick Calculator
Enter your wall length and height, pick a brick size, and the calculator returns the number of bricks to order (including a waste allowance) and the total material cost — works for UK and US brick formats.
- BTU Calculator
Estimate the cooling capacity (BTU/hr) your room needs from an air conditioner. Uses the ENERGY STAR sizing rule of 20 BTU per square foot, with adjustments for sun, occupants, and kitchens.
- Carpet Calculator
Enter your room dimensions and pick a carpet roll width — the calculator returns the number of drops, linear metres of roll, m² of carpet to order, gripper rod perimeter, and total cost. Works for UK 4 m / 5 m rolls and US 12 ft / 15 ft rolls.
- Concrete Calculator
Enter your slab or column dimensions and we work out the concrete volume (m³ and yd³), the number of bags you need, and the total cost.
- Concrete Driveway Cost Calculator
Estimate what a poured concrete driveway will cost. Enter the dimensions, slab thickness, concrete price, labor rate and reinforcement, and get total cost, concrete volume in cubic yards and installed cost per square foot.
- Decking Calculator
Enter the deck size, board width and joist spacing — we work out the board count, joist count, linear metres of timber and the approximate screws you need.
- Drywall Calculator
Enter your room dimensions and pick a sheet size — the calculator returns the number of drywall sheets to order (including waste), joint compound buckets, screws, and total material cost. Works for UK plasterboard and US gypsum board.
- Fence Calculator
Enter your total fence length, post spacing and rails per section and we work out the posts, linear rail metres, and material cost — works for timber, post-and-rail, or closeboard fencing.
- Grain Bin Capacity Calculator
Enter the inside diameter, sidewall height and peaked-roof height of a round grain bin. We use the exact geometric formula (not the rounded Purdue table factors) to give you bushels, cubic feet and grain weight for any of the six major USDA grains.
- Plywood Sheets Calculator
Enter the length and width of the surface you are sheathing, pick a panel size, and the calculator returns the number of plywood sheets to order — plus fasteners and material cost. Works for subfloors, wall sheathing, roof decking, cabinetry, and project boards.
- Roof Pitch Calculator
Enter the rise and run of your roof to get the pitch in the standard "X-in-12" notation, the slope angle in degrees, the percent grade, and the rafter length — all from one ratio.
- Square Footage Calculator
Enter your shape and dimensions and we work out the area in square feet, square metres and square yards — and the total cost if you add a rate per ft².
- Stair Calculator
Enter the floor-to-floor rise, your maximum riser height, and the tread depth (going). The calculator returns how many risers you need, the exact riser height, the total horizontal run, the stringer length, and the pitch angle — with a Blondel-formula comfort check.
- Tile Calculator
Enter your room and tile dimensions and we calculate tiles needed (with wastage), boxes to order and total cost. Mix metric and imperial freely.