Home improvement calculators

Measure twice, buy once

Most home projects start with a quantity question. How many square feet of flooring for the living room, how many bags of concrete for fence posts, how many rolls of wallpaper for a bedroom, how many tons of gravel for a driveway? Getting the number right before the trip to the hardware store saves a second trip and avoids paying for leftovers.

A few tools look at the house itself rather than materials: what an appliance costs to run, how much heating a room needs, or when moisture is likely to condense on cold walls and windows.

Matching the tool to the job

Start with the square footage calculator to get the area of a floor or a room. Pouring a slab or setting posts? The concrete calculator gives the volume and the number of bags. The stair calculator works out rise and run, stringer length and headroom, and the deck calculator counts boards, joists and screws. Use the slope calculator to convert a grade between percent, degrees and roof pitch. For running costs, the electricity cost calculator turns the wattage and hours of use of a device into kWh and a cost, and the BTU calculator estimates the heating capacity a room needs.