Home formulas

Enter Length (ft), Width (ft), and Sun factor (1=normal) for the AC BTU Calculator; retain the units printed in each label. The calculator reports BTU/hr: Rule-of-thumb sizing from floor area. This area rule does not replace a load calculation that includes insulation, climate, occupancy, and windows.

Enter Energy (kWh) and Rate ($/kWh) for the Energy Cost Calculator; retain the kWh and $/kWh units printed in the labels. The calculator reports Cost ($): Cost is energy times price per kWh. Rate ($/kWh) should include applicable charges if Cost ($) is intended to match a bill.

Enter Length (ft), Width (ft), Waste (%), and Box coverage (ft²) for the Flooring Quantity Calculator; enter percentage fields as percentage points and retain the units printed in each label. The calculator reports Area with waste and Boxes needed: Area with waste factor, then boxes of coverage. Add a practical allowance for waste, room conditions, or product specifications.

Enter Total wall length (ft), Wall height (ft), Coats, and Coverage ft²/gal for the Paint Coverage Calculator; retain the units printed in each label. The calculator reports Area × coats and Gallons: Gallons = (area × coats) / coverage per gallon. Add a practical allowance for waste, room conditions, or product specifications.

Enter Wall height (ft), Wall width (ft), Number of walls, and Roll coverage (ft²) for the Wallpaper Rolls Calculator; retain the units printed in each label. The calculator reports Rolls: Rolls = wall area ÷ coverage per roll (rounded up). Pattern matching, openings, and partial-roll waste can increase the quantity required.