How to calculate square footage
Square footage is the area of a flat surface measured in square feet. For a rectangular room, measure the length and the width in feet and multiply them. A room 12 feet long and 14 feet wide is 12 × 14 = 168 square feet.
For other shapes, use the matching formula. The calculator does this for you when you pick the shape:
| Shape | Formula |
|---|---|
| Rectangle or square | length × width |
| Circle | π × (diameter ÷ 2)² |
| Triangle | base × height ÷ 2 |
| Trapezoid | (side a + side b) ÷ 2 × height |
How to measure a room
- Measure wall to wall along the floor at the longest and widest points, using a tape measure or laser measure.
- Round to the nearest inch and write the numbers down as you go.
- If the room is L-shaped or has a bay or closet, split it into simple shapes and measure each one.
- Add each shape as its own area in the calculator. The total adds them together.
Worked example: flooring a bedroom
A bedroom measures 12 ft × 14 ft, and there is a 3 ft × 5 ft closet that will get the same flooring.
- Bedroom: 12 × 14 = 168 sq ft
- Closet: 3 × 5 = 15 sq ft
- Total: 183 sq ft. Adding 10% for cuts gives about 201 sq ft of flooring to buy.
- At $3.50 per square foot, materials come to about $705.
Flooring is usually sold by the box, so divide the square footage with waste by the coverage printed on each box and round up.
Unit conversions
- 1 square foot = 144 square inches
- 1 square yard = 9 square feet
- 1 square meter ≈ 10.764 square feet
- 1 acre = 43,560 square feet
Tips for accurate results
- Measure twice. A 3-inch error on each side of a 12 × 14 room changes the area by about 6.5 square feet.
- Do not subtract space under cabinets or appliances unless you will not cover it.
- Add more waste for diagonal tile, herringbone floors and patterned carpet that must line up.
- Keep a few spare pieces from the same batch for repairs later, since colors can vary between batches.
Last reviewed October 2026.