Square Footage Calculator
Calculate the area of a room or surface in square feet or square meters. Supports rectangle, triangle, and circle shapes.
What this calculates
Square footage tells you the area of a floor, wall, ceiling, or any flat surface — the number you need to buy paint, flooring, carpet, tile, drywall, or fertilizer. This calculator handles three common shapes: rectangles (most rooms), triangles (gables, attics), and circles (round tables, patios). It works in feet or meters and shows both square feet and square meters for the result.
Formula & how it works
Rectangle area = length × width. Triangle area = ½ × base × height. Circle area = π × radius². For a regular rectangular room measured in feet, multiply length × width to get square feet. To convert: 1 sq ft = 0.0929 sq m, and 1 sq m = 10.764 sq ft. For L-shaped rooms, split into rectangles and add the areas; for irregular shapes, approximate with the closest geometric shape and round up when buying materials.
Worked example
A bedroom is 12 ft × 14 ft = 168 sq ft (about 15.6 sq m). A triangular gable wall with a 16 ft base and 6 ft height is ½ × 16 × 6 = 48 sq ft. A round patio with a 5 ft radius is π × 25 ≈ 78.5 sq ft. When buying materials, add 10 % for waste — so for the bedroom, plan on flooring for ~185 sq ft.
Frequently asked questions
How much waste should I add for flooring or tile?
Typical waste allowances: 5–10 % for simple rectangular rooms, 10–15 % for irregular shapes or diagonal patterns, 15–20 % for herringbone or other complex patterns. The pricier the material, the more carefully you'll want to measure to minimize waste.
Do I include closets and alcoves?
For flooring, yes — anywhere you'll lay material counts. For paint, only the surfaces you'll actually paint (walls, sometimes ceiling). For real-estate listings, the rules vary by region; ANSI Z765 is the US standard and excludes garages and unfinished basements.
What's the difference between square feet and 'feet square'?
Square feet measures area: a 10 ft × 10 ft room is 100 sq ft. 'Ten feet square' means a square that's 10 feet on each side, which equals 100 sq ft. Confusingly similar terms — most contractors mean square feet.
How do I calculate an L-shaped room?
Split the L into two rectangles, calculate each separately, and add the results. For example, an L-shaped room made of a 12×10 section plus a 6×8 section = 120 + 48 = 168 sq ft. The same approach works for any room that can be broken into rectangles.
Related calculators
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- Tile CalculatorCalculate how many tiles you need for a floor or wall, including a waste allowance for cuts and breakage.
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