Supply Math

Square Footage Calculator

Measure rooms, floors, decks or yards in feet and inches. Add as many areas as you need, subtract the bits you won’t cover, and get the total in square feet, yards, meters and acres.

    $
    Total area
    – sq ft
    Square yards–
    Square meters–
    Acres–
    Estimated cost–

    Measure each rectangle separately and add them up. Tick “subtract” for things that aren’t covered, like a kitchen island.

    Square footage formula

    Area (sq ft) = length (ft) × width (ft). Inches become feet when divided by 12, so 10 ft 9 in = 10.75 ft. For a circle, area = 3.1416 × radius². For a triangle, area = ½ × base × height.

    Unit conversions

    From square feet toDivide by
    Square yards9
    Square meters10.764
    Acres43,560

    Frequently asked questions

    How do I calculate square footage?

    Multiply length × width in feet. For measurements with inches, convert the inches to feet first (divide by 12): 12 ft 6 in = 12.5 ft. For L-shaped rooms, split them into rectangles and add them up.

    How do I convert square feet to square yards or acres?

    Divide square feet by 9 for square yards, by 10.764 for square meters, and by 43,560 for acres.

    How much extra flooring should I buy?

    Add about 10% for cuts and waste with straight-lay flooring or tile, and about 15% for diagonal or herringbone patterns.

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