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Square Footage Calculator
Measure a room, house, yard or any area in feet and inches. Add up to five rectangles, triangles or circles to handle L-shaped rooms and odd shapes.
How to calculate square footage
For a rectangle or square, multiply length × width in feet. A 12 × 14 ft room is 168 sq ft. If you measured in feet and inches, convert the inches to a decimal first by dividing by 12: 12 ft 6 in is 12.5 ft.
- Triangle: ½ × base × height.
- Circle: π × radius², or 0.7854 × diameter². A 10 ft circle is 78.5 sq ft.
- L-shaped room: split it into two rectangles, work out each and add them.
Useful conversions
| 1 square yard | 9 sq ft |
| 1 square meter | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
| 1 roofing square | 100 sq ft |
Measuring a house
For the square footage of a home, real estate practice in the US (ANSI Z765) measures the finished, heated living area from the outside of the exterior walls, floor by floor. Garages, unfinished basements, porches and areas with ceilings under 7 ft are usually not counted. Your county or appraiser may measure slightly differently.
Frequently asked questions
How do I calculate square footage?
Multiply length by width in feet. For odd shapes, split the space into rectangles, triangles and circles and add them up.
How many square feet are in an acre?
43,560 square feet.