Calculator
Engineering
MathSquare Footage Calculator
Square footage calculator for flooring, tile, paint and drywall. Get area in m², ft², yd², in², cm², plus waste factor, units needed and total cost.
The Square Footage Calculator helps you calculate the area of various geometric shapes. Supports multiple shapes and units for construction, flooring, painting, and landscaping projects.
Rectangle
Circle
Triangle (Base & Height)
Parallelogram
Trapezoid
Triangle (3 Sides)
Ring (Annulus)
Rectangle Border
Sector
Have feedback? Report bugs, suggest features, or share your thoughts — we read them allWhat is a Square Footage Calculator?
A Square Footage Calculator is a versatile tool that calculates the area of various geometric shapes in different units. It's essential for construction, flooring installation, painting, landscaping, and any project requiring accurate area measurements. The calculator supports rectangles, circles, triangles, trapezoids, parallelograms, rings, sectors, and rectangle borders.
Area Formulas
Rectangle: A = L × W
Circle: A = π × r²
Triangle (Base & Height): A = (b × h) / 2
Triangle (3 Sides - Heron's formula): A = √[s(s-a)(s-b)(s-c)] (Heron's formula)
Parallelogram: A = b × h
Trapezoid: A = (a + b) × h / 2
Ring: A = π × (R² - r²)
Sector: A = (θ / 360°) × π × r²
Common Applications
- Flooring installation - calculate materials needed for rooms
- Painting estimation - determine paint coverage required
- Landscaping - measure lawn, garden, or patio areas
- Roofing calculations - estimate shingles and materials
- Tiling projects - calculate number of tiles needed
- Carpet and rug sizing
- Wall area for wallpaper or paneling
- Pool and pond surface area
- Land measurement and surveying
- Construction cost estimation based on area
Frequently Asked Questions
For a rectangular room, multiply length by width using the same unit (both in feet, both in meters, never mixed). A 12 ft × 14 ft room is 12 × 14 = 168 sq ft. For irregular L-shaped or T-shaped rooms, split the floor plan into rectangles, calculate each separately, then add the parts. For a room with a closet bumped out, calculate the main rectangle plus the closet rectangle. If the room has an angled wall or curved feature, break it into a rectangle plus a triangle (½ × base × height) or rectangle plus a half-circle (½ × π × r²). This calculator handles 7 shapes natively so you rarely need to do the geometry by hand.
The core formulas are: rectangle = length × width; circle = π × radius²; triangle = ½ × base × height; trapezoid = ½ × (base₁ + base₂) × height; parallelogram = base × height (perpendicular height, not slanted side); ring (annulus) = π × (R² − r²); circular sector = ½ × r² × θ (where θ is the angle in radians). For a rectangle border (frame), subtract inner area from outer area. Always check units before multiplying and convert at the end if the supplier or building code wants a different unit. Square feet, square meters, square inches, and square centimeters are all interchangeable with simple factors.
1 square foot equals 0.0929 square meters, and 1 square meter equals 10.764 square feet. To convert sq ft to sq m, multiply by 0.0929 (or divide by 10.764). A 1,500 sq ft house is 139.4 sq m. Note that you cannot simply use the linear conversion of 0.3048 — area scales with the square, so the factor is 0.3048² = 0.0929. The same rule applies to sq in to sq cm (multiply by 6.4516) and sq yd to sq m (multiply by 0.8361). This calculator outputs all four common area units at once so you don't have to remember any factor.
For paint, one gallon covers about 350-400 sq ft with one coat on smooth drywall; rough or porous surfaces need more, and dark-to-light color changes need two coats. For flooring (laminate, vinyl, hardwood), order 10% extra to account for cuts, defects, and future repairs; diagonal layouts need 15%. For tile, order 10% extra for standard square layouts and 15-20% for diagonal or herringbone patterns. For carpet, allow for seam waste based on roll width (typically 12 ft). Always measure the actual room rather than trusting the listed sq ft from a real estate listing — those numbers often include closets, hallways, or stairs.
This is exactly what the built-in Material & Cost Estimator does. After you calculate an area, enter a waste factor (10% for straight/grid tile or standard flooring, 15% for diagonal or herringbone, 15-20% for complex cuts), then the coverage printed on the supplier's box or can — for example 15 sq ft per box of tile, or 375 sq ft per gallon of paint. The tool computes the adjusted area = area × (1 + waste%), divides by coverage, and rounds UP to whole purchasable units, because you cannot buy 4.3 boxes of tile. Add an optional unit price and it returns the total estimated cost. Rounding up plus a waste factor is the single most important step pros take to avoid a second supply run and dye-lot mismatches. Example: a 200 sq ft floor at 10% waste is 220 sq ft; at 15 sq ft per box that is ceil(220 / 15) = 15 boxes.
It depends on which standard you follow. ANSI Z765 (used in most US real estate) measures gross living area from the exterior of finished walls and includes interior walls, closets, and hallways but excludes garages, unfinished basements, and rooms below grade. Net rentable area (commercial, BOMA standard) excludes structural columns, restrooms, and common areas. When ordering flooring or paint, always use net floor area (inside the walls, deducting cabinets and built-ins). When comparing house listings, ask whether the number is heated/cooled space, total under-roof, or gross — discrepancies of 10-15% are common between standards.
Sketch the room from above and divide it into the simplest possible shapes — usually two or three rectangles. Measure each piece's length and width independently, calculate area for each, then add them. For an L-shape, you might have a 12 × 14 main room and a 6 × 8 alcove for a total of 168 + 48 = 216 sq ft. For curved walls, treat each curve as a portion of a circle (sector or segment) and add or subtract from the surrounding rectangle. Always measure twice and from outside to outside corner; door openings, baseboards, and floor transitions should be included in the rough number, then trimmed if needed.
Square feet measure 2D area (length × width). Linear feet (or running feet) measure 1D length only — used for moldings, trim, baseboards, and rolls of fence. Board feet measure 3D lumber volume: 1 board foot = 144 cubic inches = 1 sq ft × 1 inch thick. A 2×4 that is 8 ft long contains 2 × 4 × 96 = 768 cu in = 5.33 board feet. Mixing these units is the most common ordering error: a 100-sq-ft floor needs 100 sq ft of flooring but only about 40 linear feet of baseboard, and the lumber it sits on might be measured in board feet by the cubic content.
Triangle: ½ × base × perpendicular height — not the slanted side. If you only know the three sides, use Heron's formula: area = √(s(s−a)(s−b)(s−c)) where s = (a+b+c)/2. Trapezoid: ½ × (parallel side 1 + parallel side 2) × perpendicular distance between them. Parallelogram: base × perpendicular height (drop a vertical from one corner to the opposite side). Circular sector (pie slice): ½ × r² × θ in radians, or (θ/360) × π × r² in degrees. Annulus (ring): π × (R² − r²) where R is outer radius and r is inner. This calculator implements all seven so you can pick a shape and just enter numbers.
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