Math & Measurement

Square Foot Calculator

Calculate the area of any shape in square feet or square metres — rooms, floors, walls, land, circles, triangles, L-shapes, and more. Instantly convert to sq m, sq yd, acres & hectares with tile, paint, and carpet cost estimates.

8 Shape Types
6 Unit Conversions
Cost Estimate
100% Free

Square Foot Calculator — 8 Shape Types

Select a shape, enter dimensions, choose your unit — get area in sq ft, sq m, and all major units instantly

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Rectangle
Room / Floor
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Circle
Round room / Pool
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Triangle
Sloped / roof section
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L-Shape
L-shaped room
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Trapezoid
Irregular quad
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Annulus / Ring
Circular path
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Tile Estimator
How many tiles?
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Paint / Carpet
Coverage & cost
🟩 Rectangle — Area = Length × Width
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How to measure an L-shaped room: Measure the outer rectangle (A×B), then measure the cut-out corner rectangle (C×D). Total area = A×B − C×D.
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Use this for circular paths, pool surrounds, garden rings, or round picture frames.
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📐 TOTAL AREA
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All Unit Conversions
Area Breakdown
Result Summary
Detailed Breakdown
Unit Comparison
Step-by-Step Working
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    Square Footage — Complete Guide to Area Measurement

    How to measure any room or shape, choose the right formula, and avoid the most common mistakes

    Fundamentals
    What Is Square Footage and Why Does It Matter?

    Square footage is a measure of two-dimensional area — the amount of flat space a surface occupies. It is the standard measurement unit used across real estate, construction, interior design, flooring, painting, and landscaping in the United States, Canada, and parts of South Asia. One square foot (sq ft or ft²) equals the area of a square with sides measuring exactly 1 foot (12 inches) each.

    Knowing the square footage of a room lets you order the correct amount of flooring, carpet, tile, or paint; estimate renovation costs accurately; compare property listings fairly; and comply with building regulations. In real estate, a property's price per square foot is the single most important comparison metric — knowing how to calculate it correctly can save or earn you tens of thousands of dollars or rupees.

    The key principle: area is always a two-dimensional measurement. Multiplying two lengths (e.g. 12 ft × 10 ft) always gives you an area (120 sq ft). Adding a third dimension (height) gives volume — a completely different quantity used for painting walls but not for flooring.

    Quick rule of thumb:
    1 sq m = 10.764 sq ft  ·  1 sq ft = 0.0929 sq m  ·  1 acre = 43,560 sq ft  ·  1 hectare = 107,639 sq ft  ·  1 sq yd = 9 sq ft
    Shape Formulas
    🟩
    Rectangle / Square

    Area = L × W. The simplest and most common calculation. For a square, both sides are equal: Area = s². A 12×10 ft room = 120 sq ft. A 5m×4m room = 20 sq m = 215.3 sq ft. Always measure the longest and widest points.

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    Circle

    Area = π × r² (r = radius). For a 10 ft diameter circle: r=5, Area = 3.14159 × 25 = 78.54 sq ft. Alternatively use diameter: Area = π × (d/2)². Circles appear in round pools, gazebo bases, and curved bay windows.

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    Triangle

    Area = ½ × Base × Height. Height must be perpendicular to the base. For three sides (Heron's formula): s = (a+b+c)/2, Area = √(s(s−a)(s−b)(s−c)). Common for sloped roofs, attic floors, and dormer windows.

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    L-Shape Room

    Area = Outer rectangle − Cut-out rectangle. Divide into two rectangles, calculate each, add (or subtract). Method 1: A×B − C×D. Method 2: split into two separate rectangles and add. Always verify the two methods give the same answer.

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    Trapezoid

    Area = ½ × (a + b) × h where a and b are the parallel sides and h is the perpendicular height between them. Common for rooms with one angled wall, irregular land plots, and pitched roof sections.

    ⭕
    Annulus / Ring

    Area = π × (R² − r²) where R is the outer radius and r is the inner radius. Used for circular walkways around pools, garden rings, and architectural elements like doughnut-shaped courtyards.

    Area Unit Conversion — Complete Reference Table

    Convert between all common area units — sq ft, sq m, sq in, sq yd, acres, hectares, and more

    The golden conversion: 1 sq metre = 10.7639 sq ft  ·  To go from sq ft → sq m: multiply by 0.0929  ·  To go from sq m → sq ft: multiply by 10.7639
    FromToMultiply byExample
    Square FeetSquare Metres× 0.092903100 sq ft = 9.29 sq m
    Square FeetSquare Yards× 0.111111100 sq ft = 11.11 sq yd
    Square FeetSquare Inches× 144100 sq ft = 14,400 sq in
    Square FeetAcres÷ 43,56043,560 sq ft = 1 acre
    Square MetresSquare Feet× 10.7639100 sq m = 1,076.4 sq ft
    Square MetresHectares÷ 10,00010,000 sq m = 1 hectare
    AcresSquare Feet× 43,5601 acre = 43,560 sq ft
    AcresSquare Metres× 4,046.861 acre = 4,047 sq m
    HectaresSquare Feet× 107,6391 ha = 107,639 sq ft
    HectaresAcres× 2.471051 ha = 2.471 acres
    Square YardsSquare Feet× 91 sq yd = 9 sq ft
    Square InchesSquare Feet÷ 144144 sq in = 1 sq ft
    Indian land measurements: 1 Bigha (varies by state: 1,500–6,771 sq m)  ·  1 Guntha = 101.17 sq m = 1,089 sq ft  ·  1 Cent = 435.6 sq ft = 40.47 sq m  ·  1 Marla = 272.25 sq ft  ·  1 Kanal = 5,445 sq ft  ·  1 Biswa = varies (125–200 sq m)

    How to Measure Square Footage — Room-by-Room Guide

    Professional tips for measuring every room type accurately, including irregular spaces

    Accurate measurement is more important than the formula. A calculation is only as accurate as the measurements you put into it. Always use a steel tape measure (not a cloth tape, which can stretch), measure to the nearest inch or centimetre, and record all measurements before starting any calculation.

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    Living Rooms & Bedrooms

    Measure the longest point of each wall at floor level. Do not measure at waist height — baseboards and bay windows can make the floor larger than the room appears. For square/rectangular rooms: Length × Width. For recesses and alcoves, measure them separately and add or subtract.

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    Kitchens (Irregular Shapes)

    Most kitchens are L-shaped or have peninsulas. Divide into rectangles. Sketch the room first, mark all dimensions, then add or subtract each rectangle. Measure the total perimeter too — useful for worktop and kickboard calculations.

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    Bathrooms

    Measure the total floor area including under vanities and behind the door. For tiling, also calculate wall areas (length × height for each wall, minus door and window openings). Standard door = 21 sq ft (6.6×3.2 ft). Standard window = 12 sq ft (4×3 ft).

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    Open-Plan Spaces

    Measure the total floor plate including partial walls and columns. For flooring purposes, measure the entire connected area. For heating/cooling calculations, measure each room separately. Open-plan properties are measured as one room in most real estate systems.

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    Gardens & Land Plots

    For rectangular plots: Length × Width in metres → multiply by 10.764 for sq ft. For irregular plots: break into triangles and rectangles. For sloped land, measure horizontal projection (not along the slope). GPS surveys and theodolite measurements are more accurate for large parcels.

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    Multi-Floor Buildings

    Total Floor Area = sum of all floor plates. Gross Floor Area (GFA) includes walls; Net Floor Area (NFA) excludes walls. In India, RERA carpet area = actual usable area including internal walls but excluding common areas, balconies, and terraces. Super built-up area includes proportional common areas.

    Tile & Flooring wastage guide: Standard rectangular cuts = 10% wastage. Diagonal/herringbone lay = 15% wastage. Irregular shapes = 15–20% wastage. Always round up to the nearest full box when ordering tiles. Most tile boxes contain 10–15 sq ft.

    Tile Count & Paint Coverage Reference Tables

    How many tiles per 100 sq ft, paint litres per room — ready reference for contractors and DIY

    Tile Reference
    Standard Tile Sizes — Coverage per 100 sq ft
    Tile SizeTile AreaTiles per 100 sq ftWith 10% WasteWith 15% Waste
    Paint Reference
    Paint Coverage — Litres per Room
    Room SizeWall Area1 Coat (120 sq ft/L)2 CoatsLitres rounded up
    10×10 ft, 9 ft ceiling360 sq ft3.0 L6.0 L6 L + primer
    12×10 ft, 9 ft ceiling396 sq ft3.3 L6.6 L7 L
    15×12 ft, 9 ft ceiling486 sq ft4.1 L8.1 L9 L
    20×15 ft, 10 ft ceiling700 sq ft5.8 L11.7 L12 L
    Hall 30×20 ft, 10 ft ceiling1000 sq ft8.3 L16.7 L17 L
    Wall area = 2×(L+W)×H. Standard door deduction: 21 sq ft each. Standard window deduction: 12 sq ft each. Coverage 120 sq ft/litre is standard for emulsion/latex paint.

    Frequently Asked Questions — Square Footage

    Expert answers to the most common area calculation questions from homeowners, contractors, and designers

    How do I calculate square footage of a room?
    For a rectangular room, the calculation is simply Length × Width = Area in square feet. Measure the length of the longest wall and the width of the widest point, both at floor level. Example: a room 15 feet long and 12 feet wide = 15 × 12 = 180 square feet. For rooms with alcoves or irregular shapes, break the floor plan into rectangles, calculate each one separately, then add them together. Always measure in the same unit throughout — don't mix feet and inches without converting first.
    How many square feet is a 12×12 room?
    A 12×12 room = 12 × 12 = 144 square feet (approximately 13.4 square metres). This is a very common bedroom size — compact but functional. At a typical flooring cost of $3–8 per sq ft installed, a 144 sq ft bedroom would cost $432–$1,152 for basic laminate or vinyl, or $720–$1,440 for ceramic tile. In India, at ₹80–200/sq ft, this room's flooring would cost ₹11,520–₹28,800. Always add 10–15% for cuts and wastage.
    How do I convert square feet to square metres?
    To convert square feet to square metres, multiply by 0.092903. Examples: 100 sq ft × 0.0929 = 9.29 sq m. 500 sq ft = 46.45 sq m. 1,000 sq ft = 92.9 sq m. 2,500 sq ft = 232.3 sq m. In reverse, to convert square metres to square feet, multiply by 10.7639: 50 sq m × 10.7639 = 538.2 sq ft. A quick mental shorthand: 100 sq ft ≈ 9.3 sq m, and 10 sq m ≈ 107.6 sq ft.
    How do I calculate paint needed for a room?
    Calculate the total wall area first: Wall area = 2 × (Length + Width) × Wall Height, minus deductions for doors (~21 sq ft each) and windows (~12 sq ft each). Divide by the paint's coverage rate (typically 120–130 sq ft per litre for emulsion) and multiply by the number of coats (usually 2). Example: 12×10 ft room, 9 ft ceiling, 1 door, 2 windows: Wall area = 2×(12+10)×9 = 396 sq ft. Deduct 1 door (21) + 2 windows (24) = 351 sq ft. For 2 coats: 702 sq ft ÷ 120 = 5.85 litres, round up to 6 litres. Always add 10% buffer.
    How many tiles do I need for 100 square feet?
    Number of tiles = Floor area ÷ Tile area, then add wastage. For 12×12 inch tiles (1 sq ft each): 100 ÷ 1 = 100 tiles + 10% = 110 tiles. For 18×18 inch tiles (2.25 sq ft each): 100 ÷ 2.25 = 45 tiles + 10% = 50 tiles. For 24×24 inch tiles (4 sq ft each): 100 ÷ 4 = 25 tiles + 10% = 28 tiles. For 600×600mm tiles (0.36 sq m = 3.875 sq ft each): 100 ÷ 3.875 = 26 tiles + 10% = 29 tiles. Always round up to the nearest full box (usually 5–10 tiles per box).
    What is the difference between carpet area, built-up area, and super built-up area?
    These are key Indian real estate terms: Carpet area is the net usable floor area within the apartment walls — the area where you can literally lay a carpet. It includes internal partition walls but excludes balconies and terraces. Under RERA, builders must disclose carpet area. Built-up area (also called plinth area) adds the thickness of all walls to the carpet area — typically 10–15% more than carpet area. Super built-up area (also called saleable area) adds your proportional share of common areas (lobby, staircase, lift, clubhouse) to the built-up area — typically 25–30% more than carpet area. Always compare properties using carpet area for fairness.
    How do I calculate the area of an L-shaped room?
    Divide the L-shape into two rectangles. Method 1: Measure the outer bounding rectangle (A×B), then subtract the missing corner rectangle (C×D). Total = A×B − C×D. Method 2: Split the L into two separate rectangles, measure each, and add them: Rectangle1 + Rectangle2. Both methods give identical results if measured correctly. Example: An L-shaped room 20×15 ft overall with a 6×8 ft notch cut from one corner = (20×15) − (6×8) = 300 − 48 = 252 sq ft. Verify by method 2: 20×9 + 14×6 = 180+84 = 264... if different, remeasure. The two methods must agree.
    How do I convert square feet to acres?
    Divide the square footage by 43,560: Acres = sq ft ÷ 43,560. Examples: 43,560 sq ft = 1 acre. 21,780 sq ft = 0.5 acres. 10,890 sq ft = 0.25 acres (quarter acre). 87,120 sq ft = 2 acres. 1 square mile = 640 acres = 27,878,400 sq ft. In India, 1 hectare = 2.471 acres = 107,639 sq ft = 10,000 sq m. For land measurement, also know that 1 bigha = approximately 1,500–6,771 sq m depending on the state (UP bigha = 2,709 sq m, Bengal bigha = 1,334 sq m).
    How accurate is this square foot calculator?
    This calculator uses exact mathematical formulas: Rectangle = L×W, Circle = π×r² (using JavaScript's Math.PI = 3.14159265...), Triangle base-height = ½×b×h, Heron's formula for three-sided triangles, Trapezoid = ½×(a+b)×h, Annulus = π×(R²−r²). Conversions use exact NIST-defined values: 1 ft = 0.3048 m exactly, 1 acre = 43,560 sq ft exactly. The results are accurate to 6+ decimal places — far more precise than field measurements, which are typically accurate to ±0.5 inches. For procurement purposes, always add 10–15% wastage for tiles, flooring, and paint.