Square Footage Calculator
Square footage of rooms measured in feet: rectangles, triangles and circles, minus doors and openings, with the total in sq ft, sq m or acres and a cost. How it works
Use the Square Footage Calculator
About the Square Footage Calculator
A 15 ft by 12 ft room is 180 square feet, and at $4.50 per square foot the material costs $810.00. This square footage calculator multiplies length by width for each room you add (base × height ÷ 2 for a triangle, π × radius² for a circle), takes off any area marked as an opening, sums the rest and multiplies the total by a price per square foot for an estimated cost. Lengths are in feet; the total can be shown in square feet, square metres, acres or square inches.
Common room sizes in square feet
| Length × width (ft) | Area (sq ft) |
|---|---|
| 8 × 10 | 80 |
| 10 × 10 | 100 |
| 12 × 12 | 144 |
| 12 × 15 | 180 |
| 15 × 20 | 300 |
| 9.5 × 11.25 | 106.88 |
The last row is 106.875 exactly, shown rounded to the hundredth.
Estimated cost by total area and price per square foot
| Total area (sq ft) | $2.00 | $4.50 | $8.50 | $12.00 |
|---|---|---|---|---|
| 100 | $200.00 | $450.00 | $850.00 | $1,200.00 |
| 180 | $360.00 | $810.00 | $1,530.00 | $2,160.00 |
| 280 | $560.00 | $1,260.00 | $2,380.00 | $3,360.00 |
| 300 | $600.00 | $1,350.00 | $2,550.00 | $3,600.00 |
Area times price, rounded to the cent. No waste allowance is included.
How to use this tool
- Enter the length and width of the first room in feet, and give the room a name if you like. The first room starts as a 15 by 12 foot Living Room.
- Press Add Another Room for each further room or part of one, and pick its shape: rectangle, triangle or circle. L-shaped spaces work as two or more rectangles; tick Subtract this area for a door, window or other opening.
- Type a price in Cost / Sq Ft ($). The total square footage and the estimated cost update as you type.
Frequently asked questions
- How do I calculate the square footage of a room?
- Multiply the length by the width, both in feet. A 15 by 12 foot room is 15 × 12 = 180 sq ft. For an L-shaped room, split it into rectangles, enter each as a separate room and read the total.
- How do I calculate the square footage of several rooms?
- Add one room per row and the total adds them up. A 15 × 12 living room (180 sq ft) and a 10 × 10 bedroom (100 sq ft) make 280 sq ft. The tool holds up to 50 rooms.
- How much will flooring cost for a given square footage?
- Multiply the area by the price per square foot: 280 sq ft at $4.50 is $1,260.00, and at $8.50 it is $2,380.00. This is area times one price. The tool adds no allowance for waste, cuts or pattern matching, so ask the supplier or installer how much extra to order.
- How do I enter a measurement in feet and inches?
- Turn the inches into a decimal of a foot: 9 feet 6 inches is 9.5, because 6 ÷ 12 = 0.5. A room 9.5 by 11.25 feet (11 feet 3 inches) is 106.875 sq ft, which the page shows rounded to the hundredth as 106.88 sq ft.
- How do I convert square feet to square meters or acres?
- Pick the unit under Show total in. 180 sq ft is 16.72 sq m, 0.004132 acres or 25,920 sq in, from 1 sq ft = 0.09290304 sq m and 1 acre = 43,560 sq ft. Lengths are still typed in feet, and the price stays per square foot.
- How does the calculator round areas and costs?
- It rounds once, after the exact calculation: areas to the hundredth of a square foot and costs to the cent. A room 0.1 ft by 3 ft is 0.3 sq ft, and 333.33 sq ft at $1.23 per square foot is $410.00, because the exact product is 409.9959.
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