Square Footage Calculator

Formula

square feet = length in feet × width in feet × count

Worked example

With Area length: 18 ft, Area width: 12 ft, Identical areas: 2, area per section is 216 ft².

Inputs and units

Measure both sides of the rectangle in feet. If a tape reads feet and inches, convert the inch remainder to a fraction of a foot; for example, 6 inches is 0.5 ft. The count applies only to equal-size rectangles.

• Area length (ft): Measure the finished straight edge in feet.
• Area width (ft): Measure perpendicular to the entered length.
• Identical areas: Use the count only for sections with the same dimensions.

Calculation and worked example

Multiply length by width to obtain the area of one rectangular section in square feet. Multiply that by count for total square feet. Because one square yard contains nine square feet, divide the total by nine for square yards In compact notation, square feet = length in feet × width in feet × count.

An 18 ft by 12 ft room has 216 ft². Two identical rooms have 432 ft², which is 48 yd². Measuring the rooms separately is necessary if their dimensions differ even by a little.

How to use the answer

The per-section figure helps verify each rectangle, while total area is appropriate for comparing flooring or paint coverage labels that specify square feet. The yard figure is an area conversion and does not indicate linear yards of material.

Break an L-shaped room into non-overlapping rectangles and sum their square feet. Subtract a rectangular opening only if that opening should not receive the material being estimated.

Assumptions and checks

All counted shapes are rectangles with the same dimensions and square corners. The formula is geometric area; it does not include cutting waste, overlaps, wall height, or installation patterns.

Multiplying a foot length by an inch width without conversion gives the wrong scale. A 10 ft by 10 ft floor is 100 ft², not 100 linear feet, and a square yard is nine square feet, not three.

Try an easy 1 ft by 1 ft square: the result must be 1 ft². Doubling only the length doubles area, while doubling both length and width quadruples it.

Common questions

What does the area per section result represent?

It is the two-dimensional floor or surface area of one entered rectangle in square feet; total area includes the repeat count.

What should I check before relying on this result?

Check that both measurements are in feet, the sides are perpendicular, and repeated sections truly have identical dimensions.