HOME · FREE
Square footage calculator
Measure a room, floor, yard or lot. Add shapes, subtract cut-outs, and get square feet, yards, metres and acres.
TOTAL AREA
0 sq ft
- Square yards
- 0
- Square metres
- 0
- Acres
- 0
How to calculate square footage
For a rectangle, multiply length by width in feet. A 12 × 10 ft room is 120 square feet. For a room that is not a plain rectangle, break it into rectangles, triangles or circles, find each area, then add them up. Subtract anything you are leaving out, such as a closet or fireplace.
Formulas for each shape
- Rectangle: length × width
- Triangle: base × height ÷ 2
- Circle: π × (diameter ÷ 2)²
- Trapezoid: (base 1 + base 2) ÷ 2 × height
What to do with the number
Square footage is the starting point for flooring, paint, sod and cost estimates. Once you have it, size the job with the tile calculator, the concrete calculator or the gravel calculator.
Frequently asked questions
How do I calculate square footage?
Multiply length by width, both in feet. A 12 ft × 10 ft room is 12 × 10 = 120 square feet. For inches, divide by 12 first, or pick inches in the calculator and it converts for you.
How do I calculate the square footage of an irregular or L-shaped room?
Split it into simple shapes, measure each one, and add the areas. An L-shaped room is two rectangles. Add each part as its own section in the calculator and the total updates.
How do I subtract a closet, door or cut-out?
Add it as a section and tick 'Subtract'. Use this for a kitchen island, fireplace hearth or a closet you are not tiling or painting.
How do I find the square footage of a circle?
Square footage of a circle is π × (diameter ÷ 2)². A 10 ft round patio is 3.14159 × 5 × 5 = 78.5 sq ft.
How do I find the square footage of a triangle or trapezoid?
Triangle: base × height ÷ 2. Trapezoid: (base 1 + base 2) ÷ 2 × height. Pick the shape in the calculator and enter the measurements.
How many square feet are in a square yard, square metre or acre?
A square yard is 9 sq ft, a square metre is 10.764 sq ft, and an acre is 43,560 sq ft. The results show all of these.
How much extra should I order for flooring, tile or paint?
Most guides suggest 5 to 10 percent for waste, and 10 to 15 percent for diagonal patterns or lots of cuts. Enter the percentage in the waste box to see the amount to buy.
Does this work for a lot or yard?
Yes. Measure in feet or metres, split the lot into rectangles and triangles if it is not square, and read the result in square feet, square yards, square metres and acres.
Is my data stored?
No. Everything is calculated in your browser. Nothing is uploaded or saved.