Square Footage Calculator
Measure any room — or several at once — in square feet, yards, and meters. Add a waste allowance and price per square foot to turn the measurement into a flooring, tile, or carpet estimate.
Waste allowance (for flooring/tile)
Square feet
120
Square yards
13.3
Square meters
11.1
Measure in feet with decimals — 6'6" is 6.5 ft (divide the inches by 12). For L-shaped rooms, split the floor into rectangles and add them as separate areas. Flooring installers typically order 5–10% extra for cuts; 15% for diagonal or herringbone layouts.
How to Calculate Square Footage
For a rectangular room, multiply length by width in feet. For odd layouts, break the floor plan into rectangles and triangles, calculate each piece, and add them — that's exactly what the multi-area rows above do. Convert inches to decimal feet first: divide the inches by 12, so 11'3" becomes 11.25 ft.
Formulas
Rectangle: length × width
Circle: π × (diameter ÷ 2)²
Triangle: (base × height) ÷ 2
Conversions: ÷ 9 = square yards × 0.0929 = square meters
Typical rooms: 10×10 bedroom = 100 sq ft
12×15 living room = 180 sq ft
2-car garage ≈ 400–440 sq ftFrequently Asked Questions
How many square feet is a 12×12 room?
144 square feet — length times width in feet. Other common sizes: 10×10 = 100 sq ft, 10×12 = 120 sq ft, 12×15 = 180 sq ft. For materials, convert to square yards by dividing by 9 (a 12×12 room is 16 sq yd of carpet).
How do I find the square footage of an L-shaped room?
Split the floor plan into two rectangles at the inside corner, measure each, and add them. A 12×15 main area plus a 6×8 alcove is 180 + 48 = 228 sq ft. The calculator's 'add another area' rows are built for exactly this.
How much extra flooring should I order for waste?
5–10% over the measured area for straight-lay plank or tile, and 15% for diagonal layouts, herringbone, or large-format tile in small rooms. Cuts at walls, defective pieces, and future repairs all come out of that margin — leftover boxes beat a second delivery.
Why doesn't my home's listed square footage match my room measurements?
Listed square footage follows appraisal rules (ANSI), measured from the exterior walls of finished, heated living space — so wall thickness counts, while garages, unfinished basements, and most porches don't. Adding up interior room dimensions will always come in lower.