Square footage questions, answered

To calculate square footage, multiply length by width in feet: length × width = square feet. For a 12 ft by 15 ft room, that is 12 × 15 = 180 square feet. For non-rectangular areas, split the space into rectangles or triangles, calculate each, then add the results together.

Measure the room's length and width in feet, then multiply them: length × width = square feet. A 10 ft by 12 ft bedroom is 120 sq ft. For L-shaped rooms, divide the floor into rectangles, find each area, and add them for the total square footage.

Convert inches to feet by dividing by 12, then multiply length by width. For example, 10 ft 6 in equals 10.5 ft. A space measuring 10.5 ft × 12.25 ft is about 128.6 sq ft. Our calculator has a dedicated inches field so you can enter feet and inches directly.

Square footage is area measured in feet. Measure two perpendicular sides of the space in feet and multiply them (length × width). Enter the numbers into the calculator above and the square footage updates instantly — including square meters and square yards for metric or landscaping projects.

Use the formula ½ × base × height. Measure the triangle's base and its perpendicular height in feet, multiply them, then halve the result. A triangle with a 10 ft base and 8 ft height is 0.5 × 10 × 8 = 40 square feet.

Measure the roof's footprint (length × width), then multiply by a pitch factor to account for slope. A 40 ft × 30 ft footprint is 1,200 sq ft flat; on a 6/12 pitch (factor 1.118) the actual roof area is about 1,342 sq ft. Steeper roofs need a higher pitch factor.

Multiply the room's length by its width to get the floor area in square feet, then add a waste factor of 5–10% for cuts and mistakes. For a 12 ft × 15 ft room (180 sq ft) with 10% waste, order about 198 sq ft of flooring or tile.

Multiply the total square footage by the price per square foot: square feet × price per sq ft = total cost. For 500 sq ft of flooring at $4.50 per sq ft, the cost is 500 × 4.50 = $2,250. Add labor and a waste allowance for a full project estimate.

Measure the length and width of the space in feet with a tape measure, then multiply the two: length × width = square feet. Measure to the inside of the walls at floor level for usable area. For rooms that aren't rectangular, split them into rectangles and add each area together.

Measure each room's length × width, then add the rooms together for the total. A house with a 12×15 living room (180 sq ft), two 10×12 bedrooms (240 sq ft), and a 8×10 kitchen (80 sq ft) is 500 sq ft. Finished living area usually excludes garages, unfinished basements, and open-to-below space.

Multiply the wall's width by its height: width × height = square feet. A 12 ft wide, 8 ft tall wall is 96 sq ft. For paint or wallpaper, subtract about 21 sq ft per door and 15 sq ft per window to get the paintable area you actually need to cover.

A square footage calculator — also called an SF calculator or square footage estimator — is a free tool that works out the area of a space in square feet from your measurements. It applies the correct formula for each shape (length × width for rectangles) and converts instantly to square meters, square yards, and acres.