Square footage calculator
Square footage calculator for rooms and areas.
Enter length and width in feet and inches to get the area in square feet, square yards, square meters, and acres — then jump straight to the material calculator you need.
12 x 12 room
144 sq ft
16 sq yd
Formula
length x width
feet and inches supported
Then
Estimate material
flooring, paint, concrete
Quick reference
Square footage of common room sizes
Length times width, with the same area in square yards and square meters.
| Room size | Square feet | Square yards | Square meters |
|---|---|---|---|
| 10 x 10 ft | 100 sq ft | 11.1 sq yd | 9.3 m² |
| 10 x 12 ft | 120 sq ft | 13.3 sq yd | 11.1 m² |
| 12 x 12 ft | 144 sq ft | 16.0 sq yd | 13.4 m² |
| 12 x 15 ft | 180 sq ft | 20.0 sq yd | 16.7 m² |
| 15 x 20 ft | 300 sq ft | 33.3 sq yd | 27.9 m² |
| 20 x 20 ft | 400 sq ft | 44.4 sq yd | 37.2 m² |
| 24 x 24 ft | 576 sq ft | 64.0 sq yd | 53.5 m² |
For an L-shaped room, split it into two rectangles and add the areas.
Next step
Turn square footage into a material estimate
Square footage is the starting point. Each material adds its own waste, coverage, and units — pick the calculator for what you are buying.
Conversions shown
Square feet, yards, meters, and acres
Square yards
16 sq yd
divide square feet by 9
Square meters
13.38 m²
multiply square feet by 0.0929
Acres
0.0033 acres
divide square feet by 43,560
Formula by shape
Rectangle or square
area = length x width
12 x 12 ft = 144 sq ft
Triangle
area = base x height / 2
12 ft base x 8 ft height = 48 sq ft
Circle
area = 3.1416 x (diameter / 2)²
10 ft across = 78.5 sq ft
Irregular and L-shaped rooms
Split an irregular space into rectangles, triangles, and circles. Calculate the largest piece here, then add each remaining piece to the extra-area field.
Sources
- The Home Depot square footage guide — length times width square-foot formula and room measuring
- NIST unit conversions — exact area unit conversions (sq ft, sq yd, sq m, acre)
Sources checked
Checked against
Box coverage, waste factors, and cost ranges checked against retailer calculators and published cost guides.
How we check our numbersLast updated: October 4, 2026
FAQ
Square footage calculator questions
Answers for calculating room square footage, converting to square yards, square meters, and acres, and estimating material cost.
How do you calculate square footage? + -
For a rectangle, multiply length by width in feet. If you measured in feet and inches, convert the inches to feet first (inches divided by 12), then multiply. Add the areas of separate rectangles for an L-shaped or multi-room space.
How do I find the square footage of a room? + -
Measure the length and width of the room in feet and inches, enter both, and the calculator multiplies them into square feet. For closets, bays, or an L-shape, add the extra area to the extra-area field.
How do I calculate the square footage of a triangle? + -
Multiply the base by the height and divide by 2. The height is measured straight from the base to the opposite corner, not along a sloped side. A triangle with a 12 ft base and 8 ft height is 48 sq ft.
How do I calculate the square footage of a circle? + -
Measure the diameter, halve it for the radius, then multiply the radius by itself and by 3.1416. A circle 10 ft across is 3.1416 x 5 x 5 = 78.5 sq ft.
How do I convert inches to square feet? + -
Convert each measurement to feet first by dividing the inches by 12, then multiply. A space 9 ft 6 in by 11 ft 3 in is 9.5 x 11.25 = 106.9 sq ft. If both measurements are in inches, multiply them and divide by 144.
How many square feet are in a square yard? + -
One square yard is 9 square feet. To convert square feet to square yards, divide by 9. Carpet is often ordered by the square yard, so this conversion is shown automatically.
How do I convert square feet to square meters or acres? + -
One square foot is about 0.0929 square meters, so multiply square feet by 0.0929 for square meters. One acre is 43,560 square feet, so divide square feet by 43,560 for acres. The calculator shows all three conversions at once.
How do I estimate material cost from square footage? + -
Enter a price per square foot and the calculator multiplies it by the area for a quick material budget. For a full estimate with waste, boxes, bags, or labor, use the matching material calculator linked below.