A square footage calculator tells you the area of a space in square feet, which is the number you need for buying flooring, paint, sod, carpet or tile, comparing apartments or estimating a project budget. Enter the length and width of a room and it does the math instantly, including converting inches or meters if you measured in a different unit.
For a rectangle or square, the formula is length Ă— width. A room that’s 12 feet by 15 feet is 180 square feet. For a triangle, it’s (base Ă— height) Ă· 2. For a circle, it’s Ï€ Ă— radius², so a round patio with a 6-foot radius is about 113 square feet. Irregular rooms, like an L-shaped living room, are easiest to handle by splitting them into rectangles, calculating each one and adding them together.
Example: an L-shaped room has one section that’s 10 Ă— 12 feet (120 square feet) and another that’s 6 Ă— 8 feet (48 square feet). The total is 168 square feet. If you’re buying flooring, add about 10 percent extra for cuts and waste, so plan for roughly 185 square feet.
Tips for accurate measurements: measure wall to wall at floor level, round up to the nearest inch, and measure twice. Convert inches to feet by dividing by 12, so 8 feet 6 inches is 8.5 feet. Don’t subtract small things like closets unless you won’t be flooring them; it’s better to have a little extra material than to run short halfway through a job.
Tips for getting accurate results from the Square Footage Calculator: double-check that every input uses the right units, enter numbers without commas or symbols, and run the calculation a second time with a quick estimate in your head to confirm the answer looks reasonable.
For background on the unit itself, see the square foot article on Wikipedia. Need more home project tools? Browse the free calculators on Minedit, including mulch, wallpaper, rebar and stud calculators.