Square Footage Calculator
Enter each room's size in feet and inches to get its square footage, add up several rooms or shapes (including L-shapes and circles), and see how much flooring to buy with waste, how many boxes, and the cost.
Square footage calculator
Enter feet and inches. Add as many rooms or sections as you need, and subtract areas you won't cover.
Sq ft calculator: formulas by shape
| Shape | Square feet |
|---|---|
| Rectangle | length × width |
| Square | side × side |
| L-shape | split into two rectangles and add them |
| Circle | π × (diameter ÷ 2)² |
| Triangle | base × height ÷ 2 |
| Trapezoid | (side a + side b) ÷ 2 × height |
| Ring / border | π × (outer radius² − inner radius²) |
Feet and inches: convert inches to feet by dividing by 12. A room 12 ft 6 in by 10 ft 3 in is 12.5 × 10.25 = 128.13 sq ft.
Unit conversions: 1 sq yd = 9 sq ft · 1 m² = 10.764 sq ft · 1 acre = 43,560 sq ft · 1 roofing square = 100 sq ft.
How much extra to buy: flooring installers usually add about 10% for cuts and mistakes, and around 15% for diagonal or herringbone patterns. Buying a few spare tiles from the same batch also helps with later repairs.
Common questions
How do I calculate square footage?
For a rectangle, multiply length by width in feet. A 12 ft by 15 ft room is 180 sq ft. For odd shapes, split them into rectangles, triangles or circles and add the pieces.
How do I calculate square feet with inches?
Convert inches to feet by dividing by 12 first. 10 ft 6 in = 10.5 ft, so 10 ft 6 in × 12 ft = 126 sq ft.
How many square feet is a 12 x 12 room?
144 square feet.
How much extra flooring should I buy?
About 10% more than the room's area for straight layouts, and around 15% for diagonal or herringbone patterns.
How many square feet are in an acre?
43,560 square feet.
Sources
- NIST Handbook 44: units of measurement (acre, square foot)
- NIST: SI conversion factors (square foot to square meter)
Related
General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.