Square footage calculator
A 15 ft by 12 ft 6 in room is 187.5 sq ft. Enter each area in feet and inches, pick its shape, subtract anything you won't cover, and you get the total in square feet, square yards and square meters.
Inches can be decimals or fractions, like 6.5 or 6 1/2. Leave a box empty for 0.
How each shape is measured
Feet and inches are turned into decimal feet first: 12 ft 6 in is 12 + 6 ÷ 12 = 12.5 ft.
| Shape | Formula | Example |
|---|---|---|
| Rectangle | length × width | 15 ft × 12.5 ft = 187.5 sq ft |
| Triangle | ½ × base × height | ½ × 10 ft × 6 ft = 30 sq ft |
| Circle | π × (diameter ÷ 2)² | 10 ft across = 78.54 sq ft |
| L-shape | split into two rectangles and add | 10 × 8 + 6 × 4 = 104 sq ft |
For an L-shaped room, draw one line that cuts it into two rectangles, measure each, and add them. Don't let the two parts overlap, or the corner gets counted twice. To leave out a kitchen island, a tub or a fireplace hearth, add it as its own area and switch it to Subtract.
Sources: NIST, U.S. survey foot retirement (the international foot of 0.3048 m exactly is the only US foot since January 1, 2023) and NIST Handbook 44, Appendix C (12 in = 1 ft, 9 sq ft = 1 sq yd).
Common room sizes
Square footage of typical rectangular rooms, with square yards for carpet quotes.
| Room | Square feet | Square yards | Square meters |
|---|---|---|---|
| 10 ft × 10 ft | 100 | 11.11 | 9.29 |
| 10 ft × 12 ft | 120 | 13.33 | 11.15 |
| 12 ft × 12 ft | 144 | 16 | 13.38 |
| 12 ft × 14 ft | 168 | 18.67 | 15.61 |
| 12 ft × 15 ft | 180 | 20 | 16.72 |
| 14 ft × 16 ft | 224 | 24.89 | 20.81 |
| 15 ft × 20 ft | 300 | 33.33 | 27.87 |
| 20 ft × 20 ft | 400 | 44.44 | 37.16 |
Questions people ask
- How do I calculate square feet?
- Multiply the length by the width, both in feet. A room 12 ft long and 10 ft wide is 120 sq ft. If a side has inches, divide the inches by 12 and add them to the feet first: 10 ft 9 in is 10.75 ft.
- How many square feet are in a square yard?
- Nine. A yard is 3 feet, so a square yard is 3 ft × 3 ft = 9 sq ft. Divide square feet by 9 to get square yards, which is how carpet is often priced.
- How do I convert square feet to square meters?
- Multiply by 0.09290304. NIST defines 1 foot as exactly 0.3048 meter, and 0.3048 × 0.3048 = 0.09290304. So 200 sq ft is 18.58 m².
- Should I measure to the inch?
- Yes for flooring and countertops, where a few inches change how many boxes or slabs you buy. Measure each wall at two points; rooms are rarely perfectly square, so use the longer number.
- Do I subtract closets and cabinets?
- For flooring, include closets you will floor and subtract built-in cabinets or islands you won't. For paint, use the paint calculator, which subtracts doors and windows for you.