Home Calculators

One US gallon of paint covers about 350–400 square feet in a single coat — so the first thing any paint job demands is knowing the square footage of the walls. Get that number wrong and you either run short mid-wall or haul half a can back to the store. The square footage calculator handles irregular rooms and L-shaped spaces; the paint calculator takes that area and returns gallons by coat count and finish type.

Outdoor materials follow the same logic but in three dimensions. A cubic yard of mulch spreads to roughly 100 square feet at 3 inches deep, and gravel or concrete volumes work out the same way — length times width times depth, then a unit conversion most people get wrong the first time. The 14 tools here cover the full project cycle: laying flooring, setting tile, pouring concrete slabs, spreading mulch or gravel, and filling a pool. Each one shows the formula so you can sanity-check the number before you order.

Two tools often get skipped until something goes wrong: the BTU sizing calculator and the pool volume calculator. Undersizing an air conditioner means it runs constantly and never dehumidifies properly; oversizing means it short-cycles and leaves the air clammy. Pool chemical dosing depends on accurate volume — off by 20% and chlorine levels swing unpredictably. Popular tools are listed first below, followed by the full set.