How it works
Square footage is the area of a surface in square feet. You need it to buy flooring, tiles, paint, turf or carpet, to compare homes, and to price building work. For rooms that are not a single rectangle, split them into simple shapes and add the areas.
rectangle = length × width · circle = π × radius² · triangle = base × height ÷ 2 1 m² = 10.7639 sq ft · 1 sq yd = 9 sq ft · 1 acre = 43,560 sq ftWorked examples. A room 12 ft × 15 ft = 180 sq ft = 16.72 m² = 20 sq yd. A room 4 m × 5 m = 20 m² = 215.28 sq ft. A round patio with a 10 ft radius = 314.16 sq ft. At $3.50 per sq ft, flooring the 180 sq ft room costs $630.
L-shaped and irregular rooms
Divide the room into rectangles. An L-shaped room of 20 × 12 ft with a 8 × 6 ft corner cut out = 240 − 48 = 192 sq ft. Calculate each part here and add them, or use “number of areas” for identical rooms.
Buying materials
- Flooring and tiles: add 5–10% for cutting and waste, more for diagonal layouts.
- Paint: wall area = room perimeter × wall height, minus doors and windows. One gallon covers about 350–400 sq ft per coat.
- Measure twice: round each measurement up to the nearest inch or centimetre.
Square feet and square metres
The US quotes homes in square feet; most of the world, including the Gulf and Egypt, uses square metres. A 2,000 sq ft house is about 186 m², and a 150 m² apartment is about 1,615 sq ft.
Pouring a slab? The concrete calculator gives volume and bags. Convert lengths with feet to meters, and compare material prices with the unit price calculator.