Square Footage Calculator
Find the square footage of a room or area from length and width in any unit.
Handles rectangles, circles, and triangles, with optional flooring cost.
Square footage is just area measured in feet: length times width for a rectangle. The trouble is almost never the multiplication. It is the units. People measure a room in feet and inches, or in meters, then forget to convert before multiplying, and the answer comes out wildly off. This calculator takes whatever unit you measured in (feet, inches, yards, meters, or centimeters), converts to feet first, then gives you the area.
For a plain rectangular room, measure the longest length and the width and you are done. Odd-shaped rooms are where people get stuck. The trick contractors use is to break the floor into rectangles, work out each one, and add them up. An L-shaped room is two rectangles. A room with a bumped-out closet is the main rectangle plus a small one. Set the quantity field to the number of identical areas if you are doing several rooms the same size.
Two other shapes show up often enough to include. A round patio or rug uses area equals pi times the radius squared, where the radius is half the diameter. A triangular corner is half of base times height. Pick the shape and the calculator switches formulas.
If you are buying flooring, enter a price per square foot and you get an estimated material cost. One habit worth keeping: order about 10 percent more than the bare square footage. Tile breaks, planks need trimming at the walls, and a diagonal or herringbone layout wastes more. Running out halfway through and finding the dye lot has changed is a worse problem than a few spare boxes. The cost line here is material only, not labor or underlayment.