Square Footage Calculator

What square footage is

Square footage is floor area expressed in square feet. It is used to price flooring and carpet, compare homes and rentals, size heating and cooling, and estimate cleaning or renovation work. This calculator handles rectangles; most rooms can be broken into rectangles.

Formula

Area = Σ (length × width) over every rectangle, with each dimension converted to feet first. Conversions are exact: 1 in = 1/12 ft, 1 yd = 3 ft, 1 m = 3.28084 ft (exactly 1 ÷ 0.3048).

Worked examples

L-shaped living room

1. Split the L into two rectangles: 14 ft × 12 ft and 8 ft × 6 ft.
2. 14 × 12 = 168 sq ft; 8 × 6 = 48 sq ft.
3. Total = 216 sq ft, or 216 × 0.09290304 ≈ 20.07 m².

Room measured in feet and inches

1. A room is 11 ft 6 in by 9 ft 3 in. Convert: 11.5 ft and 9.25 ft.
2. 11.5 × 9.25 = 106.375 sq ft.

Tip: enter feet-and-inches as decimal feet (6 in = 0.5 ft, 3 in = 0.25 ft), or switch the unit to inches and enter 138 and 111 (15,318 in² ÷ 144 = 106.375 sq ft).

Interpreting the result

The result is the plain measured area. When buying materials, add a waste allowance: the flooring calculator does this and counts boxes from the real coverage on the package. For walls, use the paint calculator.

Common mistakes

• Adding lengths instead of multiplying them.
• Treating 11 ft 6 in as 11.6 ft. Six inches is half a foot, 11.5 ft.
• Counting overlapping sections twice when splitting an L-shaped room.

Assumptions and limitations

Each area is treated as a perfect rectangle. Official or listed square footage for property may follow local measurement standards (for example, excluding unfinished space or areas with low ceilings), so it may differ from a simple floor measurement. For circles, triangles and other shapes, use the area calculator.

Frequently asked questions