Square Footage Calculator

Square footage is the flat area of a surface measured in feet: length times width for a rectangle. Flooring, tile, sod, paint coverage and most room-by-room estimates start from it, so getting it right is the first step of most projects. Each result is also shown in square yards (one is 9 square feet), square meters (one is about 10.764 square feet) and acres (one is 43,560 square feet).

How to use this calculator

1. Pick the shape of the first area. Most rooms are rectangles; use the triangle for an angled corner, the circle for a round patio or rug, and the trapezoid for a space whose two opposite sides are parallel but not the same length.
2. Measure wall to wall at floor level and type the numbers in. To enter feet and inches, choose ft + in in the unit menu next to the box; switching units converts what you already typed.
3. For an L-shaped room or a whole floor, split the space into simple shapes. Enter the first one, then tap Add another area for each of the others. Give each area a name, such as Kitchen or Hall, so the breakdown is easy to read.
4. If something inside your outline will not get the material, such as a kitchen island, a hearth or a pool, add it as its own area and tick Subtract. Its square footage comes off the total.
5. Read the total and the line for each area. When you are ordering material, open More options to add a percentage for waste and a price per square foot for a cost estimate.
6. Take the total to the calculator for the job: flooring, tile or sod turn square feet into boxes, tiles and pallets.

Worked examples

Square feet of common room sizes

Each cell: Area (sq ft). Inputs not in the table use the calculator's starting values.

How to measure a room

Measure along the floor from wall to wall, not along the baseboard tops or the ceiling, and take each dimension at its longest point. If a wall is not straight, measure both ends and use the larger number so you do not come up short.

Treat closets, alcoves and bay windows as their own small rectangles and add them as extra areas. Doorway openings between rooms are usually too small to matter for a total, but include them when the floor material runs through them.

L-shaped and irregular spaces

Any room with straight walls can be split into rectangles. Draw a quick sketch, divide the L into two rectangles that do not overlap, measure each one and add them as separate areas. It does not matter which way you split it: both ways give the same total.

There is often a quicker way. Measure the full rectangle that would enclose the whole space, enter it as the first area, then enter the missing corner as a second area and tick Subtract. The same trick handles a kitchen island, a fireplace hearth or a tub you are not tiling under.

For a yard or lot with angled sides, combine rectangles with triangles. A right triangle's area is half its base times its height, which is what the triangle shape works out for you.

Square feet, square yards, square meters and acres

• Square yards: divide square feet by 9, because a square yard is one yard on each side. Some materials and quotes use square yards.
• Square meters: one square meter is about 10.764 square feet, so divide square feet by that number. Product sizes from outside the US are often in square meters.
• Acres: an acre is 43,560 square feet. It does not have to be square; any shape with that area is an acre.
• Square inches: if you measured in inches, choose in as the unit and the calculator still answers in square feet.

Square footage of a house

Adding up your rooms gives the floor area you can actually cover, which is what material estimates need. The square footage printed in a listing or an appraisal is measured by its own rules, usually from the outside of the walls and counting only finished, heated space, so a total built from room measurements will not match it exactly.

For paint, the area that matters is the walls, not the floor: the paint calculator works that out from the room size and wall height.

From square feet to cubic feet: when the job has depth

Square feet describe a flat surface. For concrete, mulch or gravel, multiply the square footage by the depth in feet to get cubic feet. If the depth is in inches, divide it by 12 inches first. Suppliers often sell by the cubic yard, which is 27 cubic feet.

How to calculate the square footage of a wall

Multiply the width of the wall by its height, both in feet. Add a separate area for each window or door and tick Subtract so the total only counts what you will cover. For paint, the paint calculator does this for the whole room.

Common questions