Square Footage Calculator
Square footage here is the plan area, then the same area in square feet and square yards. A rectangle is length times width. A circle uses the diameter. An L is two rectangles added, not averaged. One square metre is 10.7639104167 square feet using 0.09290304 square feet per square foot. A square yard is that area divided by 9.
Last reviewed: 2026-10-28 · How we calculate
How we calculate
Rectangle: length × width. Circle: π × (diameter ÷ 2)². L-shape: length × width + second length × second width. Square feet = square metres ÷ 0.09290304. Square yards = square feet ÷ 9.
Worked example
A 12 × 10 ft rectangle is 120 sq ft. A 10 ft diameter circle is 78.54 sq ft. An L of 12×10 plus 8×4 is 152 sq ft.
The area the next calculator needs
Square footage is the number the flooring, paint, and seed pages all ask for before they do anything else. A rectangle is length times width. An L is two rectangles, and a circle is the diameter. Measure to the edge of the area you will cover, not to the outside of the baseboard if the floor stops inside it. Take the square-foot result to the next calculator rather than retyping a rounded metre figure.
Measuring for square footage
Square footage is the plan area. A rectangle is length times width in feet. The metric toggle shows the same area in m², and this page also keeps a square-foot line in that mode. A square yard is the square-foot figure divided by 9. There is no thickness, so there are no cubic yards. Diameter is the full distance across, and the radius is half of it. If you measured a radius, double it before you type.
How the shape becomes square feet
An L is two rectangles. Draw a line so the corner belongs to one leg only. If you drag the second rectangle back over the first, you count the overlap twice and the flooring order is long. A bay window or a notch is the same idea: positive rectangles added, or a large rectangle minus a small one. This form only adds. For a notch, calculate the outer rectangle, calculate the missing piece, and subtract. Several rooms are several runs. Add square feet to square feet. The paint calculator wants wall area, which is perimeter times height minus openings, so a floor area alone will not tell you how much paint a room needs. It will tell you the ceiling, because the ceiling is the plan area.
Using the area on another calculator
Take the square metres to the next tool rather than retyping a rounded square-foot number back into a metric field. The linear-metre calculator divides area by a board width. Tile, laminate, vinyl, hardwood, and carpet each add their own waste and pack or roll size. Mulch and gravel need a depth this page does not have. If a supplier asks for square yards of carpet, read the square-yard line. It is the square-foot line divided by 9, not a separate measurement. Rounding to two decimals can move a large area by a hundredth. For an order, keep an extra percent on the flooring page rather than arguing with the second decimal.
Checking the square footage
Odd shapes still start here. A half-circle is the circle divided by two, which you do after the result. A triangle is base times height divided by two, which you do beside this page and then add. A 45-degree bay is usually close enough to a rectangle if you measure the average length, and you should know you approximated. The calculator will not apply a waste factor for that approximation. Write the taped numbers next to the result. When the room is furnished, measure to the skirting in two directions and check the diagonals. If the diagonals disagree by more than a couple of centimetres, the room is not a rectangle and an L or a split is safer than one product of the longest sides.
Square-footage fields and starting values
Shape starts at 0. Rectangle uses length and width. Circle uses diameter. An L adds a second rectangle. Length starts at 12 ft. Room length in feet. Switch to m / cm for metres. Width starts at 10 ft. Room width in feet. Switch to m / cm for metres. Diameter starts at 10 ft. Diameter in feet. Switch to m / cm for metres. Second length starts at 8 ft. Second length in feet. Switch to m / cm for metres. Second width starts at 4 ft. Second width in feet. Switch to m / cm for metres.
Square feet for a rectangular room
These rows are the rectangle path only. A circle uses the diameter, and an L is two rectangles added on the form.
| Room | Square feet | Square metres |
|---|---|---|
| 10×10 ft | 100 sq ft | 9.29 m² |
| 12×10 ft | 120 sq ft | 11.15 m² |
| 16×12 ft | 192 sq ft | 17.84 m² |
The square-foot column is the same area the flooring and paint pages start from.
Common mistakes
- Overlapping the two legs of an L so the corner is counted twice.
- Entering a radius in the diameter field. The field is the full width of the circle.
- Mixing feet and metres in the same field. The form starts in feet. The metric toggle is where metres belong.
- Expecting wall area. This is plan area only. Paint walls use height as well.
- Averaging two rooms into one rectangle.
- Reading square yards as cubic yards. There is no thickness here.
Frequently asked questions
How do I calculate square footage of a room?
For a rectangle, multiply length by width in feet, or metres on the metric toggle, then read the square-foot line. A 12 × 10 ft room is 120 sq ft.
How do I calculate an L-shaped room?
Add the two rectangles. Keep them from overlapping. The form’s second leg starts at 8 × 4 ft, which is 32 sq ft on its own.
How do I calculate a circular area?
Pi times the radius squared. The field is the diameter, so the radius is half of what you type. A 10 ft diameter is 78.54 sq ft.
How many square feet are in a square metre?
Divide square metres by 0.09290304. The calculator does that on the square-foot line.
Can I add several rooms?
Yes. Run each shape and add the square metres, or add the square feet. Do not add a square-metre figure to a square-foot figure.
Does this include waste for tile or flooring?
No. Take the area to the tile, laminate, or linear-metre calculator and apply waste there.