Square Footage Calculator
Calculate square footage for rooms, floors, lots and projects. Rectangle, triangle, circle or trapezoid, in feet, inches, yards, meters or cm.
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About the Square Footage Calculator
This square footage calculator turns dimensions into area in square feet, with automatic conversion to square yards, square meters and acres. Pick the shape, choose your unit, and type the measurements. Add a price per square foot to estimate the cost of flooring, paint, sod, concrete or real estate, and see the amount you should order with 10 % extra for waste.
For other jobs try the area calculator, the paint calculator or the concrete calculator.
How to use it
- Choose the shape and the unit you measured in.
- Enter the length and width (or base and height, radius, or trapezoid sides).
- Optionally add the cost per square foot.
- Press Calculate to get the area in sq ft, sq yd, sq m and acres.
Square footage formulas
| Shape | Formula |
|---|---|
| Rectangle or square | length × width |
| Triangle | ½ × base × height |
| Circle | π × radius² |
| Trapezoid | ½ × (top + bottom) × height |
How to measure a room
- Measure the longest length and width wall to wall.
- Multiply them for a rectangle. For an L-shaped room, split it into two rectangles, calculate each and add them.
- Subtract areas you will not cover (built-in cabinets, a fireplace hearth).
- Add 5 to 10 % for waste when ordering flooring, tile or wallpaper.
Common conversions
| From | To sq ft |
|---|---|
| 1 square yard | 9 sq ft |
| 1 square meter | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
| 1 sq ft | 144 sq in |
Frequently asked questions
How do I calculate square footage?
For a rectangle, multiply length by width in feet. For other shapes use the formula for that shape and convert everything to feet first. This calculator does the conversion for you.
How many square feet is a 12 x 10 room?
12 × 10 = 120 square feet.
How do I calculate square footage of an L-shaped room?
Split it into two rectangles, find the area of each and add them together.
How many square feet are in an acre?
One acre is 43,560 square feet.
How many square feet are in a square yard?
One square yard equals 9 square feet.
How much extra should I order for waste?
Plan 5 to 10 % extra for straight flooring or tile layouts and 15 % for diagonal patterns.
Last reviewed: November 2026.
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