Square Footage Calculator
Enter the length and width of each room or area to get the total square footage. Add rectangles, triangles or circles and see the total in square feet, square yards, square meters and square inches.
Last updated October 20, 2026
Result
120 square feet
| Unit | Area |
|---|---|
| Square feet | 120 |
| Square yards | 13.33 |
| Square meters | 11.15 |
| Square inches | 17,280 |
Show the work
Formula: rectangle = length x width; triangle = base x height / 2; circle = pi x (diameter / 2)^2
- Area 1 (rectangle): 12 x 10 = 120 sq ft.
- Total: 120 sq ft.
- Already in feet: 120 sq ft.
- Square yards: 120 / 9 = 13.33. Square meters: 120 x 0.09290304 = 11.15. Square inches: 120 x 144 = 17,280.
Result: 120 square feet
How square footage is calculated
rectangle: length × width
triangle: base × height ÷ 2
circle: π × (diameter ÷ 2)²
For a rectangular room, multiply the length by the width, both in feet. A 12 ft by 10 ft room is 12 × 10 = 120 square feet. For an L-shaped or irregular space, split it into rectangles, work out each area and add them together.
If you measure in another unit, the calculator converts exactly: 1 foot is 12 inches, 1 yard is 3 feet and 1 foot is 0.3048 meters, so 1 square foot is 0.09290304 square meters.
See how we calculate for the formulas, sources and review schedule behind every calculator.
Also useful alongside this calculator: Concrete Calculator, Volume Calculator and Percentage Calculator.
Triangles and circles
A triangle is half of the rectangle around it: base × height ÷ 2. A triangular nook with an 8 ft base and a 6 ft height is 8 × 6 ÷ 2 = 24 square feet. Use the height measured at a right angle to the base, not the length of the slanted side.
A circle uses its diameter: π × (diameter ÷ 2)². A round patio 10 ft across is π × 5² ≈ 78.54 square feet. Measure the diameter through the centre, or double the radius.
Working in inches, yards or meters
Square units are not the same ratio as linear ones. A square foot is 12 inches by 12 inches, which is 144 square inches, and a square yard is 3 ft by 3 ft, which is 9 square feet. A room of 144 inches by 120 inches is 17,280 square inches, which is 120 square feet.
For metric measurements, 1 square foot is 0.09290304 square meters, so 228 square feet is about 21.18 square meters. Choose the unit you measured in so the conversion is applied once, to the final area, rather than to each side.
Adding waste when you buy materials
Flooring, tile and carpet are cut to fit, so buy more than the measured area. A common allowance is 10%, and more for diagonal layouts or patterned tile. For the 132 square feet in the worked example, 10% extra is 132 × 1.10 = 145.2 square feet. If a box of flooring covers 20 square feet, 145.2 ÷ 20 = 7.26, so you buy 8 boxes, always rounding up to a whole box.
Check the coverage printed on the package, since it varies by product, and keep a box of leftovers for repairs when the style may be discontinued.
Measuring an irregular space
Divide the space into rectangles and triangles, measure each, and add a row for each piece. Subtract nothing: if part of the room is cut out, measure only the pieces that are floor. Round measurements up to the next inch or half foot before ordering materials, and add extra for waste. For an L-shaped room made of a 15 ft by 12 ft rectangle and a 6 ft by 8 ft rectangle, the areas are 180 and 48 square feet, so the total is 228 square feet.
How to use the Square Footage Calculator
- Choose the unit you measured in.
- Add a row for each area: a rectangle, a triangle or a circle, and enter its measurements.
- Read the total in square feet, square yards, square meters and square inches.
- Use Copy, Print or Share to keep the result.
Worked example
A room is 12 ft by 10 ft, which is 120 square feet, and it has a 4 ft by 3 ft alcove, which is 12 square feet. The total is 132 square feet, which is about 14.67 square yards or 12.26 square meters.
| Room size | Square feet | Square meters |
|---|---|---|
| 10 ft × 10 ft | 100 | 9.29 |
| 10 ft × 12 ft | 120 | 11.15 |
| 12 ft × 12 ft | 144 | 13.38 |
| 12 ft × 15 ft | 180 | 16.72 |
| 15 ft × 20 ft | 300 | 27.87 |
| 20 ft × 20 ft | 400 | 37.16 |
Frequently asked questions
How do I calculate the square footage of a room?
Multiply the length of the room in feet by its width in feet. A 14 ft by 11 ft room is 154 square feet. Measure wall to wall at the longest and widest points and ignore furniture.
How do I calculate square feet from inches?
Multiply length by width in inches, then divide by 144, because there are 144 square inches in a square foot. Or choose inches in the calculator.
How many square feet are in a square yard?
There are 9 square feet in a square yard.
How do I measure an L-shaped room?
Split it into two rectangles, find each area and add them. Add a row for each piece in the calculator and it keeps a running total. Do not count the shared corner twice.
How much extra should I buy, and are my numbers stored?
About 10% extra for cuts and waste, rounded up to whole boxes. Your measurements run in your browser and are not saved or uploaded.