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Square footage calculator
Geometry
Result
Square feet
Square yards
Square meters
Region
Waste
Prices: national avg · Jun 2026 · sources
DiagramUpdates as you type

Calculate the square footage of a room or area, with instant conversions to square yards and square meters.

Formula

area = length × width

Method & sources
Formula basisEuclidean geometry
How we calculateArea by shape (rectangle L×W, circle πr², triangle ½bh), summed across regions.
Formula verified against the published standard above. Method last reviewed June 2026. Estimates are for planning — confirm against supplier quotes.

How it works

Square footage is simply length times width in feet. For odd shapes, split into rectangles and add them up.

Conversions

One square yard is 9 square feet; one square meter is about 10.76 square feet.

Worked example

An L-shaped room

For a simple rectangle, square footage is just length times width — a 12 x 10 ft room is 120 square feet. For an L-shaped or irregular room, split it into rectangles, calculate each, and add them up.

Say an L-shaped room is a 12 x 10 ft section plus a 6 x 8 ft section: that's 120 + 48 = 168 square feet. This split-and-add method handles almost any floor plan. For triangles, use half the base times the height; for circles, π times the radius squared.

What affects your result

Common mistakes to avoid

Where the numbers come from

Pure geometry — no estimation. Use this to feed area into the flooring, tile, paint, and other calculators.

Breaking complex shapes into rectangles

Most real spaces are not a single rectangle. The reliable method for any rectilinear shape is to divide it into non-overlapping rectangles, calculate each, and add them — an L-shape is two rectangles, a bay or bump-out is the main area plus the addition. Draw the split lines on a sketch so you do not double-count the overlap.

Triangles, circles, and conversions

Angled and curved areas need their own formulas: a triangle is half the base times the height, a circle is pi times the radius squared. Then watch the unit conversions, since you square the linear factor: one square yard is nine square feet, and one square meter is about 10.76 square feet. Mixing inches and feet is the most common error.

Frequently asked questions

How do I calculate square footage?

Multiply length by width in feet. A 12×10 room is 120 square feet.

How do I calculate the square footage of an L-shaped room?

Split the L into two non-overlapping rectangles, calculate the area of each (length times width), and add them. Sketch the split line so you do not double-count the overlap.

How many square feet are in a square yard?

One square yard is nine square feet (three feet by three feet). To convert square feet to square yards, divide by nine.

Do I subtract doors and windows from square footage?

It depends on the material. Subtract large openings for paint and wallpaper, but leave small ones in for flooring, drywall, and siding, where offcuts cannot be reused.

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