How to Calculate the Square Footage of a Room

Multiply length × width in feet. Convert inches to feet first (6 in = 0.5 ft), and add closets or bump-outs as separate rectangles.

Step 1: measure

Use a tape (or laser measure) along the floor from wall to wall, at the longest straight run in each direction. Rooms are rarely perfectly square, so measure both ends and use the larger number when you're buying material. Write it down in feet and inches.

Step 2: convert inches to feet

Divide the inches by 12: 3 in = 0.25 ft, 6 in = 0.5 ft, 9 in = 0.75 ft. So 12' 6" = 12.5 ft and 10' 3" = 10.25 ft. Don't type 12' 6" as 12.6, which is a different number. (The calculator above accepts feet-inch input directly.)

Step 3: multiply

12.5 × 10.25 = 128.1 sq ft. In square yards that's 128.1 ÷ 9 = 14.24, and in square metres it's × 0.0929 = 11.90.

Closets, alcoves and L-shaped rooms

Break the floor plan into rectangles, find each area and add them up. A 5' × 2' 6" closet is 12.5 sq ft, so the room plus closet is 140.6 sq ft. For an L-shape you can instead take the full outer rectangle and subtract the missing corner. The area calculator handles L-shapes, triangles and circles and adds as many areas as you need.

Common room sizes

What the number is used for

• Flooring and tile: add a waste allowance. See flooring with waste and the tile calculator.
• Carpet: often priced per square yard. See sq ft to sq yd.
• Paint needs wall area, not floor area. Use the paint calculator.

Listing or appraisal square footage of a home follows specific measurement standards and is usually measured from the exterior. This page is about material estimates for a single room.

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