This square footage calculator adds up the area of one or more rooms or spaces and shows the total in square feet, square yards, square meters and acres. Add an optional price per square foot and it also gives a rough cost estimate, which is handy when you are pricing flooring, carpet, paint jobs or any material sold by area.
How to Use the Square Footage Calculator
- Measure the length of the first area in feet, wall to wall at floor level.
- Measure the width of the same area in feet and enter both numbers in Area 1.
- If the space is L-shaped or you are measuring several rooms, click “+ Add another area” and enter each rectangle separately.
- Enter a price per square foot if you want a cost estimate. Leave it blank if you only need the area.
- Read the total area, plus the conversions to square yards, square meters and acres.
How the Calculation Works
Each area is treated as a rectangle. The calculator multiplies length by width for every area you enter and adds the results together to get the total square footage. Any area with a blank or zero measurement simply adds nothing.
The total is then converted into other units. Square yards are the square footage divided by 9, since one square yard is 3 feet by 3 feet. Square meters are the square footage multiplied by 0.09290304, the exact conversion factor. Acres are the square footage divided by 43,560. If you enter a price per square foot, the estimated cost is the total area multiplied by that price, rounded to the nearest dollar. The cost does not include any waste allowance, so for materials like flooring or tile, add extra before you order.
Worked example with the default values: one area that is 12 feet long and 15 feet wide, with no price entered.
- Area 1: 12 x 15 = 180 square feet
- Total area: 180 square feet
- Square yards: 180 / 9 = 20 square yards
- Square meters: 180 x 0.09290304 = 16.72 square meters
- Acres: 180 / 43,560 = 0.0041 acres
- If you enter $4.00 per square foot: 180 x 4 = $720 estimated cost
Adding a second area, for example a 6 x 8 foot closet or nook, adds 48 square feet for a total of 228 square feet.
Common Room Sizes and Square Footage
Room sizes vary a lot from house to house. The figures below are common ranges that can help you check whether your measurements look reasonable. Always measure your own space before buying materials.
| Room | Common dimensions | Approximate area |
|---|---|---|
| Small bedroom | 10 x 10 ft | 100 sq ft |
| Average bedroom | 12 x 12 ft | 144 sq ft |
| Primary bedroom | 14 x 16 ft | 224 sq ft |
| Full bathroom | 5 x 8 ft | 40 sq ft |
| Kitchen | 10 x 15 ft | 150 sq ft |
| Living room | 14 x 20 ft | 280 sq ft |
| One car garage | 12 x 22 ft | 264 sq ft |
| Two car garage | 20 x 22 ft | 440 sq ft |
Useful conversions: 1 square yard = 9 square feet, 1 square meter = about 10.76 square feet, and 1 acre = 43,560 square feet.
Tips and Common Mistakes
- Split odd shapes into rectangles. For an L-shaped room, measure it as two rectangles that do not overlap and enter each one as a separate area. Make sure you do not count the corner section twice.
- Convert inches to decimal feet. A wall that measures 12 feet 6 inches should be entered as 12.5, not 12.6. Divide the inches by 12 to get the decimal.
- Measure at floor level for flooring. Walls are not always straight. Take a measurement at each end of the room and use the larger number.
- Add waste for materials. The total here is the exact area. Flooring usually needs about 5 to 10 percent extra, and tile laid on a diagonal often needs more.
- Closets and alcoves count. If the flooring runs into closets or a hallway, measure and add those areas too.
- Price per square foot is only an estimate. Installation, underlayment, trim, delivery and tax can change the final cost considerably, so treat the cost line as a starting point.
- Circles and triangles need a different formula. This calculator handles rectangles only. For a triangle, multiply base by height and divide by 2, then enter the result as an area with a width of 1.
Frequently Asked Questions
How do I calculate the square footage of a room?
Measure the length and width in feet and multiply them. A room that is 12 feet by 15 feet is 180 square feet. For irregular rooms, break the space into rectangles, find each area, and add them together.
How many square feet are in a square yard?
There are 9 square feet in one square yard. Carpet is sometimes priced by the square yard, so divide your square footage by 9 to compare prices.
Should I include closets and the space under cabinets?
Include closets if the material will go into them. For flooring, you usually skip the area under fixed kitchen cabinets and islands, but for a whole house measurement you would measure the full room.
Is the square footage of a house the same as the sum of its rooms?
Not exactly. A listed home size is usually measured from the outside walls and includes hallways and wall thickness, so it is typically larger than the total of the room interiors you measure with this tool.