Square Footage Calculator

How to calculate square footage

Multiply the length × width of the area in feet. The result is its area in square feet: a room 12 ft by 15 ft is 180 sq ft, and a lawn 40 ft by 25 ft is 1,000 sq ft.

Every other shape has its own formula, and an odd shape is just several simple shapes added together. Measure in feet, inches, yards or meters: the calculator converts everything before it multiplies, so you never mix units.

How to use the square footage calculator

Four steps, and each one shows up in "How we calculated this" and in the PDF report.

Step 1: Pick the unit and the shape

Choose feet, inches, yards or meters, then the shape of the first section: rectangle, circle, triangle, trapezoid or oval. The fields change to the measurements that shape needs.

Step 2: Add a section for each part

An L-shaped room is two rectangles; a yard with a round bed is a rectangle plus a circle. Click "Add another section" for each piece. The total square footage updates as you type.

Step 3: Add a price per square foot in the square footage calculator

Optional: enter the price per square foot and an allowance for cuts and waste. The result adds the square feet to buy and the total cost, the numbers you need for flooring, tile, sod or pavers.

Step 4: Use the total

Copy the result, download the PDF report, or send the square feet straight to the mulch, gravel, sod, soil, topsoil or paver calculator with one click.

Square footage formulas for every shape

The exact formulas the calculator uses, with a worked example for each.

Irregular and L-shaped areas

Real rooms and yards are rarely a perfect rectangle. The reliable method is to split the area into simple shapes, measure each, and add them up:

• Sketch the area and draw lines that cut it into rectangles, triangles and circles.
• An L-shaped room or yard is two rectangles. A kidney-shaped bed is close to an oval, or a rectangle plus two half circles.
• Click “Add another section” for each piece. The total updates as you type.
• To leave out a patio inside a lawn or a kitchen island, measure it separately and subtract it from the total.

How to measure the square footage of a room or a house

Measure wall to wall at floor level, in feet and inches, and convert the inches: 12 ft 6 in is 12.5 ft. Add closets and bay windows as their own sections if the flooring runs into them.

For a whole house, add the rooms, or measure the outside walls and multiply each rectangular part. Listings report finished living area from an appraiser or the plans, which counts walls and stairs differently, so expect a sum of rooms to come out a little smaller.

Flooring, tile and carpet

Buy the room's square footage plus an allowance for cuts; the product's installation guide gives the figure, and diagonal or herringbone layouts need more. Carpet is often priced per square yard: divide square feet by 9.

Walls and paint

Wall area is the perimeter × the wall height, minus doors and windows. A 12 × 15 ft room with 8 ft walls has a perimeter of 54 ft and 432 sq ft of wall before openings. The paint can gives its coverage per gallon.

Square footage for yard and landscaping projects

Outdoor materials start from the same number. Sod and seed are sold by the area, mulch, soil and gravel by the volume (square feet × depth), and pavers by the piece per square foot. Measure lawns, beds and patios in sections and follow the curves with extra shapes.

Once you have the total, the "Use this area" links send it to the sod calculator, the mulch calculator or the paver calculator without retyping.

Cost per square foot

Total cost = square feet to buy × price per square foot. The square feet to buy is the measured area plus your allowance for cuts and waste.

Worked example: a 12 × 15 ft room is 180 sq ft. With 10% for cuts, you buy 198 sq ft; at $4.50 per sq ft the flooring costs $891. Labor quotes are usually per square foot too, so the same total works for them. Ask whether a quote will include trim, underlayment and delivery: the estimate is only as accurate as each dimension you measure.

Square feet, yards, meters and acres

Suppliers don't all use the same unit. Sod is often quoted per square foot or pallet, carpet per square yard, land per acre, product specs in square meters. Every conversion below is exact.

From square feet to cubic yards

For anything with a depth, such as concrete, soil, mulch or gravel, multiply the square feet by the depth in feet and divide by 27 to get cubic yards. The cubic yard calculator does it with the depth in inches.

Common square footage mistakes

• Mixing inches and feet. 12 ft 6 in is 12.5 ft, not 12.6 ft. Pick one unit for every measurement.
• Forgetting the waste allowance. Cuts and breakage mean you buy more than the floor area.
• Treating an odd shape as a rectangle. Split it into sections instead.
• Subtracting the wrong things. Take out fixed islands and patios, not furniture.

Get your square footage before you buy

Measure each part, add a section for every shape, and let the square footage calculator return the total square feet, square yards, square meters and acres, with the cost at your price per square foot. Download the PDF report, then send the total to the material calculator you need.

Frequently asked questions