CloudCalcAppSquare Footage Calculator
Calculate the square footage of a room or area - rectangle, circle, triangle, trapezoid, or L-shape - with instant results in square feet, square yards, square meters, or acres.
Square footage is the size of a two-dimensional area, measured in square feet (ft²) — one square foot is a square one foot on each side. To find it, measure your space in feet and apply the formula for its shape:
- Rectangle or square — length × width
- Circle — π × (diameter ÷ 2)²
- Triangle — ½ × base × height
- Trapezoid — ½ × (side A + side B) × height
- L-shape — split it into two rectangles, find each area, and add them together
For any other irregular shape, divide it into rectangles, triangles, and circles, calculate each area, and total them. To use a measurement taken in inches, divide by 12 (6 in = 0.5 ft), or use the Length Converter for other units. To change the result's units: 1 square yard = 9 ft², 1 square meter ≈ 10.7639 ft², and 1 acre = 43,560 ft². Once you know the area, you can estimate project materials — for example, how much gravel or mulch, or topsoil you need at a given depth, how many pavers a patio takes, how much sod a lawn needs, or how much stone dust a compacted base takes.
Last updated September 1, 2026
Square Footage Examples
Rectangular bedroom
- Shape:
- Rectangle
- Length:
- 12 ft
- Width:
- 10 ft
- Show result in:
- Square feet
A 12 ft by 10 ft bedroom is 12 x 10 = 120 square feet (about 13.33 square yards).
Round patio
- Shape:
- Circle
- Diameter:
- 14 ft
- Show result in:
- Square feet
A circular patio 14 ft across is about 153.94 square feet, from pi x (14 / 2) squared.
Triangular gable wall
- Shape:
- Triangle
- Base:
- 24 ft
- Height:
- 9 ft
- Show result in:
- Square feet
A gable end with a 24 ft base and 9 ft height is 1/2 x 24 x 9 = 108 square feet.
Trapezoidal garden bed
- Shape:
- Trapezoid
- Parallel side A:
- 10 ft
- Parallel side B:
- 16 ft
- Height between them:
- 6 ft
- Show result in:
- Square feet
A bed with parallel sides of 10 ft and 16 ft, 6 ft apart, is 1/2 x (10 + 16) x 6 = 78 square feet.
L-shaped living and dining room
- Shape:
- L-Shape
- Section 1:
- 20 ft x 13 ft
- Section 2:
- 9 ft x 8 ft
- Show result in:
- Square meters
Splitting the room into a 20 ft x 13 ft area and a 9 ft x 8 ft area gives (20 x 13) + (9 x 8) = 332 square feet, or about 30.84 square meters.
FAQ
How do I calculate square footage?
For a rectangular room, measure the length and width in feet and multiply them: length x width. Other shapes use their own area formula - a circle is pi x (diameter / 2) squared, a triangle is 1/2 x base x height, and a trapezoid is 1/2 x (side A + side B) x height. Select the matching shape above, enter the measurements in feet, and the calculator does the arithmetic and unit conversion for you.
How do I calculate the square footage of an odd-shaped room?
Divide the space on paper into rectangles, triangles, and parts of circles that together cover the whole floor without overlapping. Calculate the area of each piece, then add them together. Most rooms only need two or three rectangles. An L-shaped room is the most common case and has its own mode below.
Can I use this calculator for an L-shaped area?
Yes. Choose the L-Shape mode, then picture the room as two rectangles - draw a line across the inside corner to split it. Enter the length and width of each rectangle, and the calculator adds the two areas: (length 1 x width 1) + (length 2 x width 2).
How do I calculate square footage for flooring?
Measure the floor area of each room, add the rooms together for the total, then add extra for cuts and waste before ordering - about 5 to 10 percent for a straight layout, and 10 to 15 percent for a diagonal or patterned layout. Flooring is usually priced per square foot; carpet is often priced per square yard (divide square feet by 9).
How do I convert square feet to square yards?
Divide the number of square feet by 9, because one square yard is a 3 ft by 3 ft square (3 x 3 = 9 square feet). For example, 120 square feet / 9 is about 13.33 square yards. This calculator can show the result directly in square yards using the "Show result in" option.
How do I convert inches to decimal feet?
Divide the inches by 12. So 3 in = 0.25 ft, 6 in = 0.5 ft, and 9 in = 0.75 ft; a wall that is 12 ft 6 in long is 12.5 ft. Enter that decimal value in the calculator. This version uses decimal feet only - it does not accept a separate inches box.
How many square feet are in an acre?
One acre is exactly 43,560 square feet (about 4,047 square meters). An acre has no fixed shape - a square acre is roughly 208.7 ft on each side. Select the Acres option to see a large area expressed this way.
Why does the circle mode ask for diameter instead of radius?
The diameter is the full distance straight across the circle, which is easier to measure directly on a real feature like a round patio, pool, or planter than the radius (the distance from the exact center to the edge). The calculator halves the diameter internally to get the radius, then applies pi x radius squared.
Related Calculators
Gravel Calculator
Construction & DIYEstimate how much gravel you need - enter the area and depth to get the volume in cubic yards and cubic feet, an approximate weight in tons, and a bag count, with an optional allowance for waste and compaction.
Mulch Calculator
Construction & DIYEstimate how much mulch you need for a bed or landscaped area - enter the area and depth to get the volume in cubic yards and cubic feet, two- and three-cubic-foot bag counts, and an approximate weight, with an optional settling allowance.
Topsoil Calculator
Construction & DIYEstimate how much topsoil you need for a raised bed, garden, or lawn project - enter the area and depth to get the volume in cubic yards and cubic feet, one- and one-and-a-half-cubic-foot bag counts, and an approximate weight range, with an optional allowance for settling.
Paver Calculator
Construction & DIYEstimate how many pavers you need for a patio, walkway, or driveway - enter the area and your paver size to get the paver count with a waste allowance you control, plus planning estimates for the compacted gravel base and bedding sand underneath.
Sod Calculator
Construction & DIYEstimate how much sod you need for a lawn - enter the area to get the square feet and square yards to order, with a waste allowance you control plus roll, piece, and pallet estimates.
Length Converter
LengthConvert between millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles - enter a value and choose your From and To units.