Area formulas
| Shape | Formula | Example |
|---|---|---|
| Rectangle, square | length × width | 12 ft × 14 ft = 168 sq ft |
| Triangle | base × height ÷ 2 | 10 ft × 6 ft ÷ 2 = 30 sq ft |
| Circle | π × diameter² ÷ 4 | π × 6² ÷ 4 = 28.27 sq ft |
| L-shaped room | add two rectangles | 12 × 10 + 6 × 8 = 168 sq ft |
| Room minus a closet | room − closet | 168 − 12 = 156 sq ft |
Measure at floor level along the walls. If you measure in inches, choose “in” as the unit, or divide by 144 to get square feet.
Example: an L-shaped room
Square feet, square meters and square yards
| From | To | Multiply by |
|---|---|---|
| sq ft | m² | 0.0929 |
| m² | sq ft | 10.764 |
| sq ft | sq yd | ÷ 9 |
| sq in | sq ft | ÷ 144 |
Carpet is often priced per square yard, so divide your square footage by 9 before comparing prices. More conversions are in the area converter.
How much extra flooring to buy
| Material and layout | Waste allowance |
|---|---|
| Laminate, vinyl plank, straight | 5–10 % |
| Tile, straight | about 10 % |
| Diagonal layout | about 15 % |
| Herringbone, many corners | 15–20 % |
Round up to full boxes and keep one spare box for repairs: matching batches can be hard to find later.
Frequently asked questions
How do I calculate square footage?
Multiply length by width in feet. A 12 ft by 14 ft room is 168 square feet.
How do I measure an L-shaped room?
Split it into two rectangles, calculate each one and add them up. Use “Add area” in the calculator.
How many square feet is a 10×10 room?
100 square feet, or about 9.29 m².
Does square footage include closets?
For flooring, yes, if you are covering them. For real estate listings, rules vary by state and by the measuring standard used, so check with your agent or appraiser.