Calculate square footage for rectangles, circles, triangles, trapezoids and L-shapes — with unit conversion to square metres, acres and more.
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Select the shape, enter the required dimensions and click Calculate — area appears in sq ft, sq m, acres and more.
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For a rectangular room, multiply length by width: Area = Length × Width. For a 15 ft × 12 ft room: 15 × 12 = 180 sq ft. For irregularly shaped rooms, divide the space into rectangles, calculate each section, and add them together. Always measure from wall to wall at the widest points and account for any alcoves or offsets.
Measure each room (length × width in feet). Add all room totals. Add 5–10% for cuts, waste and pattern matching. For tile and hardwood: add 10%. Reduce the total by any areas that will NOT be covered (kitchen islands, built-in cabinets). Most flooring products list coverage per box or bundle — divide your total square footage by the per-box coverage.
One acre equals exactly 43,560 square feet (or 4,840 square yards, or approximately 4,047 square metres). To convert: square feet ÷ 43,560 = acres. A football field (without end zones) is approximately 48,000 sq ft or about 1.1 acres. A standard city block is typically 2–6 acres depending on city layout.
Area = π × r² (where r is the radius — half the diameter). For a circular patio with a 10 ft diameter: radius = 5 ft, Area = π × 5² = 3.14159 × 25 = 78.54 sq ft. For a semicircle: Area = (π × r²) / 2. For an oval or ellipse: Area = π × a × b (where a and b are the two radii — half the long and short axes).
1 square foot = 0.0929 square metres. To convert: sq ft × 0.0929 = sq m. For 200 sq ft: 200 × 0.0929 = 18.58 sq m. Reverse conversion: sq m × 10.764 = sq ft. For 20 sq m: 20 × 10.764 = 215.28 sq ft. A 1,500 sq ft American house is approximately 139 square metres — a common comparison when reading international real estate listings.
Calculate wall area: add the perimeter of the room × ceiling height. For a 15 × 12 ft room with 9 ft ceilings: perimeter = (15+12+15+12) = 54 ft × 9 = 486 sq ft of wall area. Subtract door openings (~21 sq ft each) and windows (~15 sq ft each). Standard paint covers 350–400 sq ft per gallon. For two coats, halve the coverage per gallon.
Divide the L-shape into two rectangles. Measure each rectangle (length × width) and add both areas. Alternatively, calculate the bounding rectangle (full length × full width) and subtract the missing corner rectangle. Double-check by measuring each segment independently. Most irregular rooms can be broken into 2–4 simple rectangles.
1 square yard = 9 square feet (3 ft × 3 ft = 9 sq ft). To convert: sq ft ÷ 9 = sq yd. For 500 sq ft of carpet: 500 ÷ 9 = 55.6 sq yd. Carpet and some other flooring materials are traditionally sold by the square yard. Other flooring (tile, hardwood, vinyl plank) is sold by the square foot. Always confirm which unit the product uses before ordering.
Typical room sizes (approximate): small bedroom = 100–120 sq ft (10 × 10 to 10 × 12 ft), standard bedroom = 130–170 sq ft, master bedroom = 200–400 sq ft, standard bathroom = 40–50 sq ft, kitchen = 100–200 sq ft, living room = 200–350 sq ft. Average US single-family home is about 2,300 sq ft; UK terraced house is about 700–900 sq ft.
For rectangular beds: Length × Width. For circular beds: π × r². For triangular areas: 0.5 × base × height. For curved or irregular beds, break into approximate geometric shapes or use the string method: lay string along the perimeter, measure the total length, then estimate the average width and multiply. Add 10% for material waste at edges and curves.
