Home & build
Find the area of a rectangular room, wall, or surface.
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Square footage calculator guide
Square footage is the starting point for almost every home project quote: flooring, paint, tile, turf, rent per square foot, and property listings all depend on it. This calculator multiplies a length and a width in feet to give area in square feet and also shows the equivalent in square metres for products sold metrically. It handles one rectangle at a time; for an L-shaped room or a house footprint, split the shape into rectangles, calculate each, and add them. Measure at floor level along the longest wall in each direction, and convert inches to decimal feet before you type them in, because 12 ft 6 in is 12.5 ft, not 12.6. For rooms with a bay or an alcove, measure the alcove as its own rectangle. The result is the plain geometric area; a flooring or paint estimate then adds its own waste or coverage factor on top.
Area (sq ft) = length (ft) × width (ft). Area (m²) = area (sq ft) × 0.092903. For inches: decimal feet = feet + inches ÷ 12.
Worked example: a room or patio measuring 20 ft long by 10 ft wide has an area of 20 × 10 = 200 sq ft. In metric units that is 200 × 0.092903 = 18.58 m². If the room were 20 ft 6 in by 10 ft 3 in, convert first: 20.5 × 10.25 = 210.13 sq ft. To buy flooring for the 200 sq ft room with a 10% cutting allowance you would need 200 × 1.10 = 220 sq ft of material. The calculator displays 200 sq ft.
Both dimensions are feet, and the result is square feet with square metres alongside. One square foot is 0.092903 m²; one square metre is 10.764 sq ft. A square yard, used for carpet, is 9 sq ft, so 200 sq ft is 22.2 sq yd. For measurements in metres, multiply each by 3.2808 to get feet, or multiply metres × metres and divide by 0.092903.
The square footage calculator returns a quantity to buy, not a guarantee of coverage. Substrate condition, waste from cuts, spillage, and settling all push real consumption above the theoretical figure, which is why most trades order a margin on top. Check the coverage rate printed on the product you actually purchase, because it varies between brands and mixes. On this page the figure rests entirely on length and width, so start there if the square footage calculator returns something you did not expect.
Good to know: writing 12 ft 6 in as 12.6 instead of 12.5 is the most common error and overstates area by nearly 1%; larger inch values distort it more. Measure the room, not the furniture layout, and include the floor under fitted units if flooring will go there. Property square footage conventions differ: US listings often use exterior gross area, while UK and EU floor plans use internal area, so the same house can differ by 10% or more between sources.
Construction quantities are planning estimates. Confirm product yield, waste, site conditions, structural requirements, and local code with the supplier or qualified professional.
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How it works
Find the area of a rectangular room, wall, or surface. This tool explains the calculation so you can adjust the assumptions to match your situation.
Worked example
With Length = 20 ft · Width = 10 ft → 200 sq ft (surface area including allowance). Change an input above and this example updates with your numbers.
Common questions
Measure the length and width in feet at floor level and multiply them. A 20 × 10 ft room is 200 sq ft. For an L-shaped room, split it into two rectangles, calculate each, and add the results.
A 20 ft by 10 ft room is 20 × 10 = 200 square feet, which is 18.58 square metres or 22.2 square yards. Flooring for it with a 10% cutting allowance would be 220 sq ft.
Multiply square feet by 0.092903. 200 sq ft × 0.092903 = 18.58 m². To go the other way, multiply square metres by 10.764. For a quick mental check, divide square feet by 10.8; a 1,000 sq ft apartment is about 93 m².
Convert each measurement to decimal feet by dividing the inches by 12 and adding to the feet. 12 ft 6 in is 12.5 ft; 10 ft 9 in is 10.75 ft. Then multiply: 12.5 × 10.75 = 134.38 sq ft.
A square yard is 3 ft × 3 ft, so 9 square feet. Carpet is often priced per square yard: divide square feet by 9, so a 200 sq ft room is 22.2 sq yd.