Square Feet Calculator
Add rectangles, circles, triangles and L-shaped areas in any unit and get the total square feet, square metres and acres.
Split an irregular room into simple shapes and add each one. The total updates as you type.
Total area
180 square feet
16.72 m² · 20 sq yd · 0.0041 acres
What this page cannot tell you
The area of the shapes you entered, flat and measured horizontally. Real estate square footage follows its own measuring standards (which spaces count, wall thickness, ceiling height), which this page does not apply.
How to calculate square feet
- Pick the unit. Feet, inches, yards, metres or centimetres.
- Add each area. Choose its shape and enter its measurements.
- Add more areas. Split an irregular space into simple shapes.
- Read the total. Square feet, square metres, square yards and acres, plus cost.
10 things people measure in square feet
Flooring
A homeowner measures an L-shaped living room for new floors.
Carpet
Someone converts square feet to square yards for carpet pricing.
Paint and wallpaper
A DIYer finds the area of a wall.
Rent per square foot
A small business compares retail spaces.
Garden beds
A gardener measures a round bed.
Sod and seed
Someone measures a lawn in several sections.
Roofing estimates
A homeowner measures a gable section.
Concrete pads
A builder measures a trapezoid pad.
Metric plans
Someone converts metres from a floor plan to square feet.
Land in acres
A buyer converts a lot's square feet to acres.
How the area is worked out
Rectangle = length × width; circle = π × (diameter ÷ 2)²; triangle = base × height ÷ 2; trapezoid = (a + b) ÷ 2 × height; L-shape = the outer rectangle minus the missing corner. Each is converted to feet first.
Conversions: 1 ft = 0.3048 m exactly; 1 square yard = 9 sq ft; 1 acre = 43,560 sq ft (NIST Handbook 44, Appendix C).
Limits: the area of the shapes you enter, measured flat. Real estate listings follow their own measuring standards (what counts as living area), which this page does not apply.
Sources
Frequently asked questions
How do I calculate square feet?
Multiply length by width in feet. A 12 × 15 ft room is 180 sq ft.
How do I measure an L-shaped room?
Choose L-shape, or split it into two rectangles and add both.
How do I convert square metres to square feet?
Multiply by 10.7639.
How many square feet in an acre?
43,560.
How do I find the square feet of a circle?
π × radius². A 10 ft circle is about 78.5 sq ft.
Can I enter inches?
Yes, choose inches; the result is still in square feet.
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