Calculator
Square Footage Calculator
Calculate the square footage of any space — rectangles, circles, triangles, or combinations. Results convert instantly to sq ft, sq yd, sq m, and acres. Add multiple regions for irregular rooms.
How to calculate square footage
- Measure the longest sides of the space in feet (or inches, divided by 12).
- Multiply length × width for rectangles. The result is square footage.
- For circles: π × (diameter ÷ 2)². For a 10 ft circle: 3.14 × 25 = 78.5 sq ft.
- For irregular shapes: break into rectangles and triangles, calculate each, then add the results.
- Convert to acres: divide square feet by 43,560. One acre = 43,560 sq ft.
Common rooms & lots
| Space | Sq ft |
|---|---|
| 10 × 10 bedroom | 100 |
| 12 × 14 bedroom | 168 |
| 16 × 20 living room | 320 |
| 20 × 30 driveway | 600 |
| 1/4 acre lot | 10,890 |
| 1/2 acre lot | 21,780 |
| 1 acre lot | 43,560 |