Square Footage Calculator

+ Add another area Calculate Square Footage

How square footage is calculated

For any rectangular area, square footage is simply:

Square feet = length (ft) × width (ft)

For a whole room, floor, or house, measure each rectangular section separately and add the results — that's exactly what the "+ Add another area" button above is for. If your measurements are in inches, divide each one by 12 first (or divide the final square-inch total by 144).

How do I measure an L-shaped or irregular room? Split it into rectangles on paper, calculate each rectangle, and add them together. For a triangular area, use length × width ÷ 2. For a circle, use π × radius² (radius is half the diameter).

How much extra material should I buy? Almost never the exact figure. Flooring and tile pros typically add 10% for cuts, breakage, and future repairs — 15–20% for diagonal or patterned layouts, stairs, or rooms with lots of corners. Sod and mulch are usually ordered with 5–10% extra. The waste allowance above applies that cushion for you.

Does square footage include closets and hallways? For material estimates, yes — measure and add any area that will actually be covered. (Real-estate "living area" square footage follows different rules and usually excludes garages, unfinished basements, and unheated spaces.)