How to calculate square footage
Square footage is the area of a flat surface measured in square feet. Measure each side in feet and multiply. If a room is L-shaped or irregular, split it into rectangles, calculate each one, and add them together.
Rectangle = Length × Width
Circle = π × (Diameter ÷ 2)²
Triangle = ½ × Base × Height
Worked example: 12 × 15 ft bedroom
12 × 15 = 180 square feet. That is 20 square yards (180 ÷ 9) or 16.7 square meters.
Unit conversions
| From | To square feet |
|---|---|
| 1 square yard | 9 sq ft |
| 1 square meter | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
| 144 square inches | 1 sq ft |
Measuring tips
- Measure wall to wall at floor level, not at the baseboard top.
- Round each measurement up to the nearest inch, then convert inches to feet (divide by 12).
- For closets and bump-outs, measure them as separate rectangles.
Frequently asked questions
How do I convert inches to square feet?
Multiply length by width in inches, then divide by 144. A 48 × 96 inch sheet is 4,608 ÷ 144 = 32 sq ft.
How do I calculate square footage of an irregular room?
Divide the room into rectangles and triangles, calculate each area separately, and add them up.
How many square feet are in an acre?
One acre is 43,560 square feet, about the size of a football field without the end zones.
Does square footage include walls?
For flooring, measure the open floor only. Home listings usually report gross living area measured from exterior walls.