Square Footage Calculator
Pick a shape, either a rectangle or square, a triangle, a circle or a trapezoid, and the unit you measured in: feet, inches, yards, meters or centimeters. Enter the dimensions and the calculator returns the area in square feet and in square meters, to 2 decimal places. For flooring, add a waste percentage, a price per square foot or square meter and the coverage of one box, or leave them empty. You then see the area to buy, the cost and the whole boxes. For a room made of several shapes, work out each one and add the results.
Flooring (optional)
How to use the Square Footage Calculator
- Enter your numbers in the Square Footage Calculator above.
- Press the Calculate button to see the result.
- To try other numbers, change any value and press the button again.
The area formulas
Rectangle = L × W · · · Triangle = ½ × B × H · · · Circle = π × R² · · · Trapezoid = ½ × (B1 + B2) × H
The calculator works out the area in the unit you typed, then converts it with 1 ft = 0.3048 m, 1 in = 0.0254 m and 1 yd = 0.9144 m. One square foot is 0.09290304 square meters. For flooring, area to buy = area × (1 + waste %), cost = area to buy × price and boxes = area to buy ÷ coverage per box, rounded up. Each figure comes from the numbers as you typed them and is rounded once, at the end.
Worked example
A 14 ft × 16 ft bedroom is 224.00 square feet, or 20.81 square meters. A 4 ft × 8 ft closet adds 32.00 square feet, so the two together cover 256 square feet. Measured in meters, a 4 m × 5 m room is 20.00 square meters, or 215.28 square feet. Flooring the bedroom with 10% waste at $3.50 per sq ft means 246.40 sq ft to buy and $862.40. In boxes of 20 sq ft that is 13 whole boxes, which cost $910.00. The 10% and the prices are examples.
Frequently asked questions
How much waste should I add for flooring?
Use the allowance your installer or the product instructions call for, because it depends on the material, the pattern and the shape of the room. The calculator starts at 0% and does not choose a figure for you. Type yours in the Waste % field and the area to buy goes up by that share.
Why do the whole boxes cost more than the flooring cost?
The flooring cost prices exactly the area to buy. Flooring sold by the box has to be bought in whole boxes, so that cost covers some extra area. 246.40 sq ft in boxes of 20 sq ft takes 13 boxes, which hold 260 sq ft.
How do I measure an L-shaped room?
Split it into rectangles, run each one through the calculator and add the square feet together. An L-shaped room is two rectangles. Include closets and alcoves if you plan to cover them too.
Which conversion factors does it use?
The exact ones NIST lists: a foot is 0.3048 meters, an inch is 2.54 centimeters, a yard is 0.9144 meters and a square foot is 0.09290304 square meters. A square meter therefore comes to about 10.76 square feet.