CalcArcade.

Square Footage Calculator

Measure a room, lot or garden by entering its dimensions. Choose a shape and get the area in several units at once.

Your numbers

Result

How we calculate it

Rectangle area = length × width. Triangle area = ½ × base × height. Circle area = π × (diameter ÷ 2)².

Conversions: 1 square yard = 9 square feet, 1 square meter = 10.7639 square feet, and 1 acre = 43,560 square feet.

Assumptions and limits

  • For L-shaped or irregular rooms, split the space into rectangles, calculate each and add them together.
  • Measure to the finished wall surface for flooring and to the outer edge for roofing or paving.

Frequently asked questions

How do I measure the square footage of a room?

Measure the length and width in feet and multiply them. For an L-shaped room, split it into two rectangles and add the results.

How many square feet are in an acre?

One acre is 43,560 square feet.

How much extra flooring should I buy?

Many installers recommend 5 to 10 percent extra for cuts and mistakes, and more for diagonal or patterned layouts.

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Worked example (a fixed example using the starting numbers, it does not change as you type)

Inputs: Shape = Rectangle; Dimension A (feet) = 14; Dimension B (feet; not used for circles) = 18.

  • Area 252.00 sq ft
  • Square yards 28.00
  • Square meters 23.41
  • Acres 0.0058

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Last reviewed: . Formulas and assumptions are described on our methodology page. For information only; not professional advice.