Calculate the area of a rectangle in square feet from length and width in inches, feet, yards, centimeters, or meters. Also converts to sq in, sq yd, sq m, and acres.
Whether you are measuring a room for new flooring, estimating paint coverage, or sizing a garden bed, the first step is usually calculating the area in square feet. This tool does exactly that: enter the length and width of any rectangle — in inches, feet, yards, centimeters, or meters — and get the area in square feet instantly. It also converts the result to square inches, square yards, square meters, and acres so you can compare across unit systems.
The core formula is simply Area = Length × Width, but the practical challenge is unit conversion. A room measured at 4.5 m × 3.2 m needs to be converted to square feet for U.S. flooring products, while a plot measured in yards needs acres. This calculator handles all the conversions automatically.
Additional outputs include the perimeter (useful for baseboards and trim), the diagonal (helpful for measuring or cutting), and the converted dimensions in feet. A reference table shows how different area units relate to each other, and a common room sizes table highlights typical spaces so you can double-check your result.
Perfect for homeowners, contractors, interior designers, real estate agents, and students dealing with area and unit conversions.
This tool is designed for the real job people usually have in front of them: taking two measured dimensions and turning them into usable square footage for pricing, ordering, and comparison. It also removes the conversion friction that happens when measurements come in inches, yards, centimeters, or meters but material is sold by the square foot. In one step you can see the area, perimeter, diagonal, and alternate unit conversions needed for flooring, paint estimates, trim planning, or room-size checks.
Area (ft²) = Length (ft) × Width (ft) 1 ft = 12 in = 0.3048 m 1 yd = 3 ft 1 ft² = 144 in² = 0.0929 m² 1 acre = 43,560 ft² Perimeter = 2(L + W) Diagonal = √(L² + W²)
Result: 300 sq ft
A 15 × 20 ft rectangle has an area of 15 × 20 = 300 sq ft, which equals 43,200 sq in, 33.33 sq yd, or 27.87 sq m. The perimeter is 70 ft and the diagonal is 25 ft.
Square footage for a rectangle comes from multiplying two perpendicular dimensions after both have been converted into feet. That sounds simple, but measurement errors usually happen before the multiplication step. People mix inches and feet, measure to drywall instead of finished surface, or forget that a 15 foot 6 inch span is not the same as 15.6 feet. Converting the dimensions first and then multiplying keeps the result consistent and makes downstream conversions to square yards, square meters, or acres reliable.
Rectangular area calculations appear in nearly every property and construction workflow. Flooring, carpet, underlayment, sod, roof decking, insulation panels, and paint coverage often start with a rectangular estimate. The perimeter and diagonal matter too: perimeter helps with trim, edging, or baseboards, while the diagonal is useful for layout checks and cut planning. A quick area conversion is also important when suppliers quote material in metric units but your project drawings are in feet and inches.
Raw square footage is usually the starting point rather than the final purchase quantity. Flooring installers often add 5% to 10% waste for straight installs and more for angled or patterned layouts. Garden fabric, turf, and tile may require extra material for trimming around edges. Once you know the rectangle area in square feet, compare it with the converted values and the common room-size table to confirm the scale looks reasonable before you order anything. That small validation step can prevent expensive overbuying or a last-minute shortage.
Enter your length and width in inches and select "Inches" as the unit. The calculator converts to feet (÷ 12 each dimension) and computes the area in square feet.
One square yard = 9 square feet (3 ft × 3 ft = 9 ft²). Use this as a practical reminder before finalizing the result.
Multiply square meters by 10.764 to get square feet. The calculator does this automatically.
One acre = 43,560 square feet. It is about the size of a football field without end zones.
Break the room into rectangular sections, calculate each one, and add them together. Each section can use this calculator.
Calculate the square footage and add 10% for waste (cuts and errors). For diagonal or patterned installations, add 15%.