How to calculate square footage
Square footage is the area of a floor measured in square feet. For a rectangular room, multiply its length by its width in feet: a 15 by 12 foot bedroom is 180 square feet. If a room is L-shaped or has an alcove, split it into rectangles, calculate each one, and add them together. This calculator lets you enter up to four areas and totals them automatically, which is ideal for estimating flooring across several rooms or the area of an L-shaped space. Switch to metric to work in meters and square meters.
Adding a waste allowance
When you buy flooring, tile or carpet, you always need more than the exact floor area, because pieces are cut to fit walls, doorways and corners, and some will be damaged or mis-cut. The usual allowance is about 5% to 10% for straight installations of laminate, vinyl plank or carpet, 10% to 15% for tile, and 15% to 20% for diagonal or herringbone patterns, which create more offcuts. The calculator adds 10% by default. Keeping a box of spare material is also wise, because the same color or batch may be hard to find later if a plank or tile needs replacing.
Estimating cost
Enter a price per square foot (or per square meter) and the calculator multiplies it by the area including waste to estimate the material cost. Remember that flooring is often sold by the box, so you will need to round up to whole boxes; divide your total by the coverage printed on each box and round up. Installation is usually priced separately per square foot. Also budget for underlayment, trim, transition strips, adhesive or grout, and removal of old flooring. Getting several quotes and comparing them on a per-square-foot basis makes it easier to spot outliers.
Square footage of a house
The square footage advertised for a home is usually the finished, heated living area, measured from the exterior walls. In the US many appraisers follow the ANSI Z765 standard, which excludes garages, unfinished basements and areas with ceilings lower than 7 feet. Real estate listings may use different methods, so two homes with the same advertised size can feel quite different. Price per square foot, the sale price divided by the living area, is a popular way to compare homes in the same neighborhood, but it ignores lot size, condition and layout. For property purchases, our mortgage calculator can help you estimate monthly costs. If you are measuring for a sale or appraisal, have a professional confirm the figure.
Frequently asked questions
How do I calculate square feet?
Multiply length by width, both in feet. A 10 by 12 foot room is 120 square feet.
How much extra flooring should I buy?
Typically 5% to 10% extra for straight layouts and 15% or more for diagonal or patterned layouts.
How do I convert inches to feet for square footage?
Divide inches by 12. For example, 10 feet 6 inches is 10.5 feet.
How many square feet is a 12x12 room?
144 square feet, or about 13.4 square meters.