How to use the square footage calculator
- Choose the units you measured in: feet, inches, yards, meters or centimeters.
- For each room or section, pick its shape and enter the two measurements. Decimals work, so 12 ft 6 in is 12.5 ft.
- Click Add area for more rooms. The total updates as you type.
- For flooring, tile or sod, keep a waste allowance, and add a price per square foot to estimate the cost.
Measuring an L-shaped room? Split it into two rectangles and add both. To leave out a kitchen island or a closet, add it as its own area and put the word “minus” in its name.
Square footage formulas
Square footage is the area of a flat surface measured in squares that are one foot on each side. Use the formula that matches the shape:
Always measure in one unit before you multiply. Mixing feet and inches is the most common mistake: 10 ft × 6 in is not 60 square feet; it is 10 × 0.5 = 5 square feet.
Worked example
A living room measures 16 ft × 14 ft and the attached dining area is 10 ft × 12 ft.
16 × 14 = 224 sq ft, plus 10 × 12 = 120 sq ft, for a total of 344 sq ft. With 10% waste you would buy flooring for 378.4 sq ft, or 379 sq ft rounded up.
At $3.50 per sq ft, the material would cost about $1,324.
Area unit conversions
| Unit | In square feet |
|---|---|
| 1 square inch | 0.00694 sq ft (1 ÷ 144) |
| 1 square yard | 9 sq ft |
| 1 square meter | 10.764 sq ft |
| 1 acre | 43,560 sq ft |
| 1 hectare | 107,639 sq ft |
Carpet is often sold by the square yard, so divide square feet by 9. Lawn care and land are priced per acre, so divide by 43,560.
How much extra flooring or tile to buy
Pieces get cut to fit walls, doorways and corners, and some break. Buying extra also means you have matching spares for repairs later. Common allowances:
- 5–7% for wall-to-wall carpet or a simple rectangular room
- 10% for laminate, vinyl plank or hardwood laid straight
- 15% for tile, diagonal or herringbone patterns, and rooms with many corners
Boxes are sold whole, so divide the area with waste by the square feet per box and round up.
Frequently asked questions
How do I calculate square footage of a room?
Measure the length and width in feet and multiply them. A 12 ft by 15 ft room is 12 × 15 = 180 square feet. For irregular rooms, split the floor into rectangles, find each area and add them together.
How do I convert inches to square feet?
Multiply the length and width in inches, then divide by 144. A 48 in by 60 in area is 2,880 square inches, which is 20 square feet. You can also choose Inches as the unit and the calculator converts for you.
How do I find the square footage of a house?
Measure each room and hallway, or measure the outside walls and multiply. Official listings usually count finished, heated living space only, so garages, unfinished basements and porches are left out.
How many square feet is a 10 by 12 room?
A 10 ft by 12 ft room is 120 square feet. With a 10% waste allowance you would buy 132 square feet of flooring.
What is the difference between square feet and linear feet?
Square feet measure area: length times width. Linear feet measure length only, which is used for trim, baseboard, fencing and countertops edges.