Add up the square footage of rooms, L-shaped spaces, circles and triangles in any units, then see square yards, square meters, acres and total cost.
How to use the square footage calculator
- Choose the unit you measured in. Every area uses the same unit.
- Enter the first area. For a rectangle that’s length and width; for a circle, the diameter; for a triangle, the base and the height.
- Add more areas for L-shaped rooms, several rooms or a whole floor. Each area’s size shows under it, and the total updates as you type.
- Enter a price per square foot to estimate the cost of flooring, paint, sod or a contractor’s quote.
Square footage formulas
Rectangle: area = length × width Circle: area = π × (diameter ÷ 2)² Triangle: area = base × height ÷ 2 Square yards = square feet ÷ 9 Acres = square feet ÷ 43,560 Square meters = square feet × 0.09290304
Measure in feet with a decimal (10.5 ft) or in inches and pick Inches above; the calculator converts. A foot is exactly 0.3048 m, so a
square foot is exactly 0.09290304 m² (NIST).
Worked example: an L-shaped living area
- Split the L into two rectangles: 20 × 15 ft and 10 × 12 ft.
- Areas: 20 × 15 = 300 ft² and 10 × 12 = 120 ft².
- Total: 300 + 120 = 420 ft², which is 46.67 yd² or 39.02 m².
A round patio 12 ft across is π × 6² = 113.1 ft². The triangular gable end of a house 24 ft wide with a 6 ft rise is
24 × 6 ÷ 2 = 72 ft². A 12 × 14 ft bedroom is 168 ft², or 18.67 yd² of carpet before waste.
How to measure a room
- Measure wall to wall at floor level, and round to the nearest inch. Measure each wall; old rooms are often not square.
- Split odd shapes into rectangles, triangles and circles, measure each and add them here.
- Include closets if the flooring or paint job includes them, and leave out areas under built-in cabinets if it doesn’t.
- Add waste for materials. Flooring, tile and sod need extra for cuts; ask the product maker or installer how much.
Area conversions
| From | To | Multiply by |
|---|---|---|
| Square feet | Square yards | ÷ 9 |
| Square feet | Square meters | 0.09290304 |
| Square meters | Square feet | 10.7639 |
| Square feet | Acres | ÷ 43,560 |
| Square inches | Square feet | ÷ 144 |
Questions
How do I calculate the square footage of a room?
Multiply the length by the width in feet. A 12 × 14 ft room is 168 ft².
How do I find the square footage of an L-shaped room?
Split it into two rectangles, find each area and add them. The example above comes to 420 ft².
How many square feet are in an acre?
43,560 square feet.
How do I convert square feet to square yards?
Divide by 9, since a square yard is 3 ft × 3 ft. The square yard calculator does this with waste and cost.
Sources
- NIST Guide to the SI, Appendix B.8: Factors for units listed alphabetically, National Institute of Standards and Technology.
Used for: Exact inch and foot definitions; cubic foot, cubic yard and gallon conversions.