Square Footage Calculator
How do I calculate the square footage of a room?
Multiply the length by the width in feet. A 12 x 14 ft room is 12 × 14 = 168 sq ft (18.67 sq yd or 15.61 sq m). Turn inches into decimal feet first: a room 12 ft 6 in by 14 ft 3 in is 12.5 × 14.25 = 178.13 sq ft. For an L-shaped room, split it into rectangles and add their areas.
This square footage calculator finds the area of a rectangle, circle, triangle or trapezoid from measurements in feet or meters. It shows the result in square feet, square meters, square yards and acres at the same time, so you can switch between flooring, carpet and land units without a separate converter.
It is built for homeowners, renters, DIYers and contractors sizing a floor, patio, lawn or garden bed. If you also enter a cost per unit of area, the tool multiplies it by the area to give a quick budget figure for materials or labor that are priced by the square foot.
Enter your details
How to Use the Square Footage Calculator
- 1
Choose feet or meters
Use the Feet / Meters toggle at the top to set the unit for every dimension you type in.
- 2
Pick the shape
Select the Rectangle, Circle, Triangle or Trapezoid tab that best matches the area you measured.
- 3
Enter the dimensions
Type length and width, the radius, base and height, or both bases and the height, depending on the shape.
- 4
Add a cost (optional)
Enter a price per unit of area to see an estimated total cost next to the area results.
- 5
Read the results
The total area appears instantly along with square feet, square meters, square yards and acres. Use Clear to start over.
How the square footage formula works
Area is always one measurement multiplied by another, so your inputs must be in the same unit. Convert inches to feet first by dividing by 12 (for example, 8 ft 6 in is 8.5 ft).
The calculator uses the standard geometry formula for each shape, then converts the result. Square yards are square feet divided by 9, and acres are square feet divided by 43,560. Metric areas are converted with 1 sq m = 10.764 sq ft.
Rectangle: A = length × width | Circle: A = π × radius² | Triangle: A = ½ × base × height | Trapezoid: A = ½ × (top base + bottom base) × height- For a circle, enter the radius, which is half the diameter. A 12 ft wide round patio has a 6 ft radius.
- For a triangle, the height is the straight-line distance from the base to the opposite point, measured at a right angle to the base, not the length of a sloped side.
- For a trapezoid, the two bases are the parallel sides and the height is the distance between them.
Worked example: a 12 × 14 ft bedroom
You measure a bedroom at 12 ft by 14 ft and want to price new flooring.
- Area: 12 × 14 = 168 sq ft.
- Square meters: 168 × 0.0929 = 15.61 sq m.
- Square yards (useful for carpet): 168 ÷ 9 = 18.67 sq yd.
- Acres: 168 ÷ 43,560 = 0.0039 acres.
- If you enter a cost per sq ft, the estimate is simply 168 times that price. The tool does not add waste, so a price for flooring should be applied to the area you will actually buy.
Common room sizes in square feet
Use this table as a quick sanity check against your own measurements. Square yards are rounded to two decimals.
| Room size (ft) | Square feet | Square yards | Square meters |
|---|---|---|---|
| 10 × 10 | 100 | 11.11 | 9.29 |
| 10 × 12 | 120 | 13.33 | 11.15 |
| 12 × 12 | 144 | 16 | 13.38 |
| 12 × 14 | 168 | 18.67 | 15.61 |
| 12 × 16 | 192 | 21.33 | 17.84 |
| 14 × 16 | 224 | 24.89 | 20.81 |
| 16 × 20 | 320 | 35.56 | 29.73 |
| 20 × 20 | 400 | 44.44 | 37.16 |
Inches to decimal feet
Tape measures read in feet and inches, but the calculator needs decimal feet. Divide the inches by 12 and add them to the whole feet, or use this table.
| Inches | Decimal feet | Inches | Decimal feet |
|---|---|---|---|
| 1 in | 0.083 | 7 in | 0.583 |
| 2 in | 0.167 | 8 in | 0.667 |
| 3 in | 0.25 | 9 in | 0.75 |
| 4 in | 0.333 | 10 in | 0.833 |
| 5 in | 0.417 | 11 in | 0.917 |
| 6 in | 0.5 | 12 in | 1 |
Round and angled areas
Use the Circle tab for round patios, rugs and tree rings, entering the radius (half the diameter). The Triangle and Trapezoid tabs cover angled corners, bay windows and wedge-shaped garden beds.
| Shape | Measurements | Area |
|---|---|---|
| Circle | 10 ft across (5 ft radius) | 78.54 sq ft |
| Circle | 12 ft across (6 ft radius) | 113.1 sq ft |
| Circle | 16 ft across (8 ft radius) | 201.06 sq ft |
| Triangle | 10 ft base, 8 ft height | 40 sq ft |
| Trapezoid | 10 ft and 14 ft parallel sides, 8 ft apart | 96 sq ft |
Measuring L-shaped and irregular rooms
The calculator handles one shape at a time. For an L-shaped room or any odd layout, split the floor into simple rectangles, triangles or half-circles, run each piece separately, and add the results.
Example: an L-shaped living area can be split into a 20 × 12 ft section (240 sq ft) and a 10 × 8 ft section (80 sq ft), for a total of 320 sq ft. Make sure the pieces do not overlap, or you will count the corner twice.
Floor area versus wall area
Square footage usually means floor area, which is what you need for flooring, tile, carpet and ceilings. Paint, wallpaper and drywall are bought by wall area instead: the room's perimeter times the wall height. A 12 × 14 ft room has 168 sq ft of floor but 416 sq ft of wall with 8 ft ceilings.
Once you have the area, the material calculators take it from there: the flooring calculator and tile calculator add waste and count boxes or tiles, and the paint calculator works out gallons from the room size. Outdoors, the same area feeds the sod calculator and mulch calculator.
Edge cases: closets, bump-outs and sloped ceilings
- Closets and alcoves: measure them as their own rectangles and add them if the flooring runs into them.
- Bay windows and angled walls: measure the main rectangle, then add the bump-out as a trapezoid (its two parallel sides and the depth between them).
- Obstacles: kitchen islands, built-in cabinets and fireplace hearths can be subtracted if the material will not go underneath. Calculate their footprint and take it away.
- Sloped ceilings: the floor area does not change, but in attic rooms the space under a low ceiling may not count as living area in real estate or code terms.
Tips for accurate measurements and ordering
- Measure wall to wall at floor level, and measure each dimension in two places. Rooms are rarely perfectly square, so use the larger number.
- The calculator gives the exact area with no waste added. For flooring, add about 5 to 10 percent for cuts, and more for diagonal or herringbone layouts.
- Materials sold by the box or roll should be rounded up to the next full unit after you add waste.
- In meters mode, the area and cost use square meters, so enter a price per square meter rather than per square foot.
- For real estate listings, appraisals or permits, local rules decide what counts as living area. Use this tool for estimates and rely on a licensed appraiser or your local building office for official figures.
Features
- Rectangle, circle, triangle, trapezoid shapes
- Convert sq ft to sq m, sq yd, acres
- Cost estimation per sq ft
- Feet or meters input
- Instant calculations
Frequently Asked Questions
How do I calculate the square footage of a room?
Measure the length and width of the room in feet and multiply them. A room that is 11 ft by 13 ft is 11 × 13 = 143 sq ft. If a measurement includes inches, divide the inches by 12 and add them to the feet first, so 11 ft 6 in becomes 11.5 ft. For rooms that are not rectangular, split them into simple shapes and add the areas.
How many square feet is a 12x12 room?
A 12 by 12 ft room is 144 sq ft, because 12 × 12 = 144. That equals 16 square yards (144 ÷ 9) or about 13.38 square meters. If you are buying flooring for it, plan on roughly 151 to 159 sq ft of material once you add a 5 to 10 percent waste allowance for cuts, then round up to full boxes.
How many square feet is a 10x10 room?
A 10 by 10 ft room is 100 sq ft, because 10 × 10 = 100. That is 11.11 square yards or about 9.29 square meters. A 14 x 16 ft room is 224 sq ft and a 20 x 20 ft room is 400 sq ft.
How do I find the square footage of an L-shaped room?
Divide the L into two rectangles that do not overlap, calculate each one, and add them together. For example, a 20 × 12 ft section is 240 sq ft and a 10 × 8 ft section is 80 sq ft, giving 320 sq ft in total. You can also measure the full outer rectangle and subtract the missing corner; both methods give the same answer.
How do I convert square feet to square yards for carpet?
Divide square feet by 9, because one square yard is 3 ft by 3 ft. A 168 sq ft bedroom is 168 ÷ 9 = 18.67 sq yd. The calculator shows square yards automatically next to the square feet result. Carpet also comes in fixed roll widths, so the amount you buy can be higher than the room area once seams are planned.
How many square feet are in an acre?
One acre is exactly 43,560 sq ft, which is about 4,047 sq m. A lot that measures 100 ft by 200 ft is 20,000 sq ft, or about 0.46 acres. The calculator shows acres to four decimal places, which is handy for yards, garden plots and small parcels. For legal property boundaries, rely on a survey rather than your own tape measurements.
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